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Foster 4 Series Couplers

The Foster 4 Series is the 3/8" body industrial interchange, one of the most common air coupler sizes for shop and industrial use. This collection includes 4 Series couplers and plugs in brass, steel, and stainless with NPT, hose barb, push-on, and reusable terminations. Filter by thread, material, and coupler or plug to match your line.

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Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass Save 20% Save %
$ 646.00
$ 646.00 - $ 646.00
$ 646.00
$ 517.00
$ 517.00 - $ 517.00
$ 517.00

Foster SL4204, 3/8" Industrial Coupler x 3/8" Female NPT, 4 Series, Automatic Sleeve Lock, Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster SL4204 is a Brass 3/8" industrial coupler from the Foster 4 Series — a hig...

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$ 646.00
$ 646.00 - $ 646.00
$ 646.00
$ 517.00
$ 517.00 - $ 517.00
$ 517.00
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Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass Save 20% Save %
$ 567.00
$ 567.00 - $ 567.00
$ 567.00
$ 453.00
$ 453.00 - $ 453.00
$ 453.00

Foster FM4204, 3/8" Industrial Coupler x 3/8" Female NPT, 4 Series, Automatic, Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster FM4204 is a Brass 3/8" industrial coupler from the Foster 4 Series — a hig...

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$ 567.00
$ 567.00 - $ 567.00
$ 567.00
$ 453.00
$ 453.00 - $ 453.00
$ 453.00
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Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass Save 20% Save %
$ 636.00
$ 636.00 - $ 636.00
$ 636.00
$ 508.00
$ 508.00 - $ 508.00
$ 508.00

Foster SL4004, 3/8" Industrial Coupler x 1/4" Female NPT, 4 Series, Automatic Sleeve Lock, Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster SL4004 is a Brass 3/8" industrial coupler from the Foster 4 Series — a hig...

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$ 636.00
$ 636.00 - $ 636.00
$ 636.00
$ 508.00
$ 508.00 - $ 508.00
$ 508.00
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Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass Save 20% Save %
$ 563.00
$ 563.00 - $ 563.00
$ 563.00
$ 450.00
$ 450.00 - $ 450.00
$ 450.00

Foster FM4004, 3/8" Industrial Coupler x 1/4" Female NPT, 4 Series, Automatic, Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster FM4004 is a Brass 3/8" industrial coupler from the Foster 4 Series — a hig...

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$ 563.00
$ 563.00 - $ 563.00
$ 563.00
$ 450.00
$ 450.00 - $ 450.00
$ 450.00
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Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
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$ 572.00
$ 572.00 - $ 572.00
$ 572.00
$ 457.00
$ 457.00 - $ 457.00
$ 457.00

Foster SD13-4, 3/8" Industrial Coupler x Reusable Hose Fitting, 3/8" ID x 13/16" OD, 4 Series, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster SD13-4 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series —...

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$ 572.00
$ 572.00 - $ 572.00
$ 572.00
$ 457.00
$ 457.00 - $ 457.00
$ 457.00
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Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
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$ 551.00
$ 551.00 - $ 551.00
$ 551.00
$ 441.00
$ 441.00 - $ 441.00
$ 441.00

Foster SD11-4, 3/8" Industrial Coupler x Reusable Hose Fitting, 3/8" ID x 3/4" OD, 4 Series, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster SD11-4 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series —...

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$ 551.00
$ 551.00 - $ 551.00
$ 551.00
$ 441.00
$ 441.00 - $ 441.00
$ 441.00
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Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
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$ 641.00
$ 641.00 - $ 641.00
$ 641.00
$ 514.00
$ 514.00 - $ 514.00
$ 514.00

Foster BLSD9-4, 3/8" Industrial Coupler x Reusable Hose Fitting, 3/8" ID x 11/16" OD, 4 Series, Ball Lock, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster BLSD9-4 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series ...

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$ 641.00
$ 641.00 - $ 641.00
$ 641.00
$ 514.00
$ 514.00 - $ 514.00
$ 514.00
Save 20% Save %
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
Save 20% Save %
$ 537.00
$ 537.00 - $ 537.00
$ 537.00
$ 430.00
$ 430.00 - $ 430.00
$ 430.00

Foster SD9-4, 3/8" Industrial Coupler x Reusable Hose Fitting, 3/8" ID x 11/16" OD, 4 Series, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster SD9-4 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series — ...

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$ 537.00
$ 537.00 - $ 537.00
$ 537.00
$ 430.00
$ 430.00 - $ 430.00
$ 430.00
Save 20% Save %
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
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$ 630.00
$ 630.00 - $ 630.00
$ 630.00
$ 505.00
$ 505.00 - $ 505.00
$ 505.00

Foster BLSD7-4, 3/8" Industrial Coupler x Reusable Hose Fitting, 3/8" ID x 5/8" OD, 4 Series, Ball Lock, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster BLSD7-4 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series ...

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$ 630.00
$ 630.00 - $ 630.00
$ 630.00
$ 505.00
$ 505.00 - $ 505.00
$ 505.00
Save 20% Save %
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
Save 20% Save %
$ 528.00
$ 528.00 - $ 528.00
$ 528.00
$ 422.00
$ 422.00 - $ 422.00
$ 422.00

Foster SD7-4, 3/8" Industrial Coupler x Reusable Hose Fitting, 3/8" ID x 5/8" OD, 4 Series, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster SD7-4 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series — ...

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$ 528.00
$ 528.00 - $ 528.00
$ 528.00
$ 422.00
$ 422.00 - $ 422.00
$ 422.00
Save 20% Save %
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
Save 20% Save %
$ 616.00
$ 616.00 - $ 616.00
$ 616.00
$ 492.00
$ 492.00 - $ 492.00
$ 492.00

Foster SB7-4, 3/8" Industrial Coupler x Reusable Hose Fitting, 1/4" ID x 5/8" OD, 4 Series, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster SB7-4 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series — ...

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$ 616.00
$ 616.00 - $ 616.00
$ 616.00
$ 492.00
$ 492.00 - $ 492.00
$ 492.00
Save 20% Save %
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
Save 20% Save %
$ 629.00
$ 629.00 - $ 629.00
$ 629.00
$ 503.00
$ 503.00 - $ 503.00
$ 503.00

Foster SB5-4, 3/8" Industrial Coupler x Reusable Hose Fitting, 1/4" ID x 9/16" OD, 4 Series, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster SB5-4 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series — ...

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$ 629.00
$ 629.00 - $ 629.00
$ 629.00
$ 503.00
$ 503.00 - $ 503.00
$ 503.00
Save 20% Save %
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
Save 20% Save %
$ 599.00
$ 599.00 - $ 599.00
$ 599.00
$ 480.00
$ 480.00 - $ 480.00
$ 480.00

Foster SB3-4, 3/8" Industrial Coupler x Reusable Hose Fitting, 1/4" ID x 1/2" OD, 4 Series, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster SB3-4 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series — ...

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$ 599.00
$ 599.00 - $ 599.00
$ 599.00
$ 480.00
$ 480.00 - $ 480.00
$ 480.00
Save 20% Save %
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
Save 20% Save %
$ 611.00
$ 611.00 - $ 611.00
$ 611.00
$ 489.00
$ 489.00 - $ 489.00
$ 489.00

Foster 1814W, 3/8" Industrial Coupler x 1/2" Push-On Hose Stem, 4 Series, Water, Brass/SS

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 1814W is a Brass/SS 3/8" industrial coupler from the Foster 4 Series — a h...

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$ 611.00
$ 611.00 - $ 611.00
$ 611.00
$ 489.00
$ 489.00 - $ 489.00
$ 489.00
Save 20% Save %
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
Save 20% Save %
$ 514.00
$ 514.00 - $ 514.00
$ 514.00
$ 411.00
$ 411.00 - $ 411.00
$ 411.00

Foster BL1814, 3/8" Industrial Coupler x 1/2" Push-On Hose Stem, 4 Series, Ball Lock, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster BL1814 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series —...

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$ 514.00
$ 514.00 - $ 514.00
$ 514.00
$ 411.00
$ 411.00 - $ 411.00
$ 411.00
Save 20% Save %
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
Save 20% Save %
$ 487.00
$ 487.00 - $ 487.00
$ 487.00
$ 390.00
$ 390.00 - $ 390.00
$ 390.00

Foster 1814, 3/8" Industrial Coupler x 1/2" Push-On Hose Stem, 4 Series, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 1814 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series — a...

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$ 487.00
$ 487.00 - $ 487.00
$ 487.00
$ 390.00
$ 390.00 - $ 390.00
$ 390.00
Save 20% Save %
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
Save 20% Save %
$ 579.00
$ 579.00 - $ 579.00
$ 579.00
$ 462.00
$ 462.00 - $ 462.00
$ 462.00

Foster 1714W, 3/8" Industrial Coupler x 3/8" Push-On Hose Stem, 4 Series, Water, Brass/SS

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 1714W is a Brass/SS 3/8" industrial coupler from the Foster 4 Series — a h...

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$ 579.00
$ 579.00 - $ 579.00
$ 579.00
$ 462.00
$ 462.00 - $ 462.00
$ 462.00
Save 20% Save %
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
Save 20% Save %
$ 480.00
$ 480.00 - $ 480.00
$ 480.00
$ 384.00
$ 384.00 - $ 384.00
$ 384.00

Foster BL1714, 3/8" Industrial Coupler x 3/8" Push-On Hose Stem, 4 Series, Ball Lock, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster BL1714 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series —...

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$ 480.00
$ 480.00 - $ 480.00
$ 480.00
$ 384.00
$ 384.00 - $ 384.00
$ 384.00
Save 20% Save %
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
Save 20% Save %
$ 443.00
$ 443.00 - $ 443.00
$ 443.00
$ 354.00
$ 354.00 - $ 354.00
$ 354.00

Foster 1714, 3/8" Industrial Coupler x 3/8" Push-On Hose Stem, 4 Series, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 1714 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series — a...

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$ 443.00
$ 443.00 - $ 443.00
$ 443.00
$ 354.00
$ 354.00 - $ 354.00
$ 354.00
Save 20% Save %
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
Save 20% Save %
$ 591.00
$ 591.00 - $ 591.00
$ 591.00
$ 475.00
$ 475.00 - $ 475.00
$ 475.00

Foster 4904S, 3/8" Industrial Coupler x 1/2" Hose ID, 4 Series, Steam/EPDM, Brass body, Brass sleeve, SS valve

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 4904S is a Brass body, Brass sleeve, SS valve 3/8" industrial coupler from...

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$ 591.00
$ 591.00 - $ 591.00
$ 591.00
$ 475.00
$ 475.00 - $ 475.00
$ 475.00
Save 20% Save %
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
Save 20% Save %
$ 602.00
$ 602.00 - $ 602.00
$ 602.00
$ 482.00
$ 482.00 - $ 482.00
$ 482.00

Foster BL4904, 3/8" Industrial Coupler x 1/2" Hose ID, 4 Series, Ball Lock, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster BL4904 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series —...

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$ 602.00
$ 602.00 - $ 602.00
$ 602.00
$ 482.00
$ 482.00 - $ 482.00
$ 482.00
Save 20% Save %
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
Save 20% Save %
$ 485.00
$ 485.00 - $ 485.00
$ 485.00
$ 388.00
$ 388.00 - $ 388.00
$ 388.00

Foster 4904, 3/8" Industrial Coupler x 1/2" Hose ID, 4 Series, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 4904 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series — a...

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$ 485.00
$ 485.00 - $ 485.00
$ 485.00
$ 388.00
$ 388.00 - $ 388.00
$ 388.00
Save 20% Save %
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
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$ 574.00
$ 574.00 - $ 574.00
$ 574.00
$ 459.00
$ 459.00 - $ 459.00
$ 459.00

Foster 4804W, 3/8" Industrial Coupler x 3/8" Hose ID, 4 Series, Water, Brass/SS

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 4804W is a Brass/SS 3/8" industrial coupler from the Foster 4 Series — a h...

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$ 574.00
$ 574.00 - $ 574.00
$ 574.00
$ 459.00
$ 459.00 - $ 459.00
$ 459.00
Save 20% Save %
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
Save 20% Save %
$ 611.00
$ 611.00 - $ 611.00
$ 611.00
$ 489.00
$ 489.00 - $ 489.00
$ 489.00

Foster 4804S, 3/8" Industrial Coupler x 3/8" Hose ID, 4 Series, Steam/EPDM, Brass body, Brass sleeve, SS valve

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 4804S is a Brass body, Brass sleeve, SS valve 3/8" industrial coupler from...

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$ 611.00
$ 611.00 - $ 611.00
$ 611.00
$ 489.00
$ 489.00 - $ 489.00
$ 489.00
Save 20% Save %

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