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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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$ 184.00
$ 184.00 - $ 184.00
$ 184.00
$ 147.00
$ 147.00 - $ 147.00
$ 147.00

Foster 47-4, 4 Series, Industrial Plug, 5/16" Hose Barb, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 47-4 is a Steel 3/8" industrial plug from the Foster 4 Series — a high-flo...

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$ 184.00
$ 184.00 - $ 184.00
$ 184.00
$ 147.00
$ 147.00 - $ 147.00
$ 147.00
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$ 114.00
$ 114.00 - $ 114.00
$ 114.00
$ 91.00
$ 91.00 - $ 91.00
$ 91.00

Foster 71-4, 4 Series, Industrial Plug, 3/8" Push-On Hose Barb, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 71-4 is a Steel 3/8" industrial plug from the Foster 4 Series — a high-flo...

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$ 114.00
$ 114.00 - $ 114.00
$ 114.00
$ 91.00
$ 91.00 - $ 91.00
$ 91.00
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$ 124.00
$ 124.00 - $ 124.00
$ 124.00
$ 99.00
$ 99.00 - $ 99.00
$ 99.00

Foster 49-4, 4 Series, Industrial Plug, 1/2" Hose Barb, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 49-4 is a Steel 3/8" industrial plug from the Foster 4 Series — a high-flo...

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$ 124.00
$ 124.00 - $ 124.00
$ 124.00
$ 99.00
$ 99.00 - $ 99.00
$ 99.00
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$ 446.00
$ 446.00 - $ 446.00
$ 446.00
$ 356.00
$ 356.00 - $ 356.00
$ 356.00

Foster 4304, 4 Series, Industrial Coupler, Manual, 3/8" Male NPT, Brass, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 4304 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series — a...

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$ 446.00
$ 446.00 - $ 446.00
$ 446.00
$ 356.00
$ 356.00 - $ 356.00
$ 356.00
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$ 563.00
$ 563.00 - $ 563.00
$ 563.00
$ 450.00
$ 450.00 - $ 450.00
$ 450.00

Foster FM4604, 4 Series, Industrial Coupler, Automatic, 1/4" Hose Barb, Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster FM4604 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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$ 202.00
$ 202.00 - $ 202.00
$ 202.00
$ 161.00
$ 161.00 - $ 161.00
$ 161.00

Foster 38-4, 4 Series, Industrial Plug, 1/8" Male NPT, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 38-4 is a Steel 3/8" industrial plug from the Foster 4 Series — a high-flo...

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$ 202.00
$ 202.00 - $ 202.00
$ 202.00
$ 161.00
$ 161.00 - $ 161.00
$ 161.00
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$ 131.00
$ 131.00 - $ 131.00
$ 131.00
$ 106.00
$ 106.00 - $ 106.00
$ 106.00

Foster 51-4, 4 Series, Industrial Plug, 1/4" Push-On Hose Barb, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 51-4 is a Steel 3/8" industrial plug from the Foster 4 Series — a high-flo...

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$ 131.00
$ 131.00 - $ 131.00
$ 131.00
$ 106.00
$ 106.00 - $ 106.00
$ 106.00
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$ 476.00
$ 476.00 - $ 476.00
$ 476.00
$ 381.00
$ 381.00 - $ 381.00
$ 381.00

Foster 71-4B, 4 Series, Industrial Plug, 3/8" Push-On Hose Barb, Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 71-4B is a Brass 3/8" industrial plug from the Foster 4 Series — a high-fl...

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$ 476.00
$ 476.00 - $ 476.00
$ 476.00
$ 381.00
$ 381.00 - $ 381.00
$ 381.00
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$ 191.00
$ 191.00 - $ 191.00
$ 191.00
$ 154.00
$ 154.00 - $ 154.00
$ 154.00

Foster 81-4, 4 Series, Industrial Plug, 1/2" Push-On Hose Barb, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 81-4 is a Steel 3/8" industrial plug from the Foster 4 Series — a high-flo...

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$ 191.00
$ 191.00 - $ 191.00
$ 191.00
$ 154.00
$ 154.00 - $ 154.00
$ 154.00
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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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$ 485.00
$ 485.00 - $ 485.00
$ 485.00
$ 388.00
$ 388.00 - $ 388.00
$ 388.00

Foster 4604, 4 Series, Industrial Coupler, Manual, 1/4" Hose Barb, Brass, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 4604 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
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$ 510.00
$ 510.00 - $ 510.00
$ 510.00
$ 407.00
$ 407.00 - $ 407.00
$ 407.00

Foster 4704, 4 Series, Industrial Coupler, Manual, 5/16" Hose Barb, Brass, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 4704 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series — a...

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$ 510.00
$ 510.00 - $ 510.00
$ 510.00
$ 407.00
$ 407.00 - $ 407.00
$ 407.00
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$ 499.00
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$ 499.00
$ 400.00
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$ 400.00

Foster 4804, 4 Series, Industrial Coupler, Manual, 3/8" Hose Barb, Brass, Steel

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

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$ 499.00
$ 499.00 - $ 499.00
$ 499.00
$ 400.00
$ 400.00 - $ 400.00
$ 400.00
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$ 485.00
$ 485.00 - $ 485.00
$ 485.00
$ 388.00
$ 388.00 - $ 388.00
$ 388.00

Foster 4904, 4 Series, Industrial Coupler, Manual, 1/2" Hose Barb, 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
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$ 443.00
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$ 443.00
$ 354.00
$ 354.00 - $ 354.00
$ 354.00

Foster 1714, 4 Series, Industrial Coupler, Manual, 3/8" Hose Barb (Push-On), 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
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$ 487.00
$ 487.00 - $ 487.00
$ 487.00
$ 390.00
$ 390.00 - $ 390.00
$ 390.00

Foster 1814, 4 Series, Industrial Coupler, Manual, 1/2" Hose Barb (Push-On), 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
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$ 570.00
$ 570.00 - $ 570.00
$ 570.00
$ 457.00
$ 457.00 - $ 457.00
$ 457.00

Foster FM4704, 4 Series, Industrial Coupler, Automatic, 5/16" Hose Barb, Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster FM4704 is a Brass 3/8" industrial coupler from the Foster 4 Series — a hig...

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$ 570.00
$ 570.00 - $ 570.00
$ 570.00
$ 457.00
$ 457.00 - $ 457.00
$ 457.00
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$ 636.00
$ 636.00 - $ 636.00
$ 636.00
$ 508.00
$ 508.00 - $ 508.00
$ 508.00

Foster FM1814, 4 Series, Industrial Coupler, Manual, 1/2" Hose Barb (Push-On), Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster FM1814 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
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$ 361.00
$ 361.00 - $ 361.00
$ 361.00
$ 289.00
$ 289.00 - $ 289.00
$ 289.00

Foster PD13-4, 3/8" Industrial Plug x Reusable Hose Fitting, 3/8" ID x 13/16" OD, 4 Series, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster PD13-4 is a Steel 3/8" industrial plug from the Foster 4 Series — a high-f...

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$ 361.00
$ 361.00 - $ 361.00
$ 361.00
$ 289.00
$ 289.00 - $ 289.00
$ 289.00
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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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$ 278.00
$ 278.00 - $ 278.00
$ 278.00
$ 223.00
$ 223.00 - $ 223.00
$ 223.00

Foster PD11-4, 3/8" Industrial Plug x Reusable Hose Fitting, 3/8" ID x 3/4" OD, 4 Series, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster PD11-4 is a Steel 3/8" industrial plug from the Foster 4 Series — a high-f...

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$ 278.00
$ 278.00 - $ 278.00
$ 278.00
$ 223.00
$ 223.00 - $ 223.00
$ 223.00
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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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$ 255.00
$ 255.00 - $ 255.00
$ 255.00
$ 204.00
$ 204.00 - $ 204.00
$ 204.00

Foster PD9-4, 3/8" Industrial Plug x Reusable Hose Fitting, 3/8" ID x 11/16" OD, 4 Series, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster PD9-4 is a Steel 3/8" industrial plug from the Foster 4 Series — a high-fl...

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$ 255.00
$ 255.00 - $ 255.00
$ 255.00
$ 204.00
$ 204.00 - $ 204.00
$ 204.00
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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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$ 253.00
$ 253.00 - $ 253.00
$ 253.00
$ 202.00
$ 202.00 - $ 202.00
$ 202.00

Foster PD7-4, 3/8" Industrial Plug x Reusable Hose Fitting, 3/8" ID x 5/8" OD, 4 Series, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster PD7-4 is a Steel 3/8" industrial plug from the Foster 4 Series — a high-fl...

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$ 253.00
$ 253.00 - $ 253.00
$ 253.00
$ 202.00
$ 202.00 - $ 202.00
$ 202.00
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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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$ 280.00
$ 280.00 - $ 280.00
$ 280.00
$ 225.00
$ 225.00 - $ 225.00
$ 225.00

Foster PB7-4, 3/8" Industrial Plug x Reusable Hose Fitting, 1/4" ID x 5/8" OD, 4 Series, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster PB7-4 is a Steel 3/8" industrial plug from the Foster 4 Series — a high-fl...

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$ 280.00
$ 280.00 - $ 280.00
$ 280.00
$ 225.00
$ 225.00 - $ 225.00
$ 225.00
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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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$ 246.00
$ 246.00 - $ 246.00
$ 246.00
$ 197.00
$ 197.00 - $ 197.00
$ 197.00

Foster PB5-4, 3/8" Industrial Plug x Reusable Hose Fitting, 1/4" ID x 9/16" OD, 4 Series, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster PB5-4 is a Steel 3/8" industrial plug from the Foster 4 Series — a high-fl...

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$ 246.00
$ 246.00 - $ 246.00
$ 246.00
$ 197.00
$ 197.00 - $ 197.00
$ 197.00
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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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$ 264.00
$ 264.00 - $ 264.00
$ 264.00
$ 211.00
$ 211.00 - $ 211.00
$ 211.00

Foster PB3-4, 3/8" Industrial Plug x Reusable Hose Fitting, 1/4" ID x 1/2" OD, 4 Series, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster PB3-4 is a Steel 3/8" industrial plug from the Foster 4 Series — a high-fl...

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$ 264.00
$ 264.00 - $ 264.00
$ 264.00
$ 211.00
$ 211.00 - $ 211.00
$ 211.00
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