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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 %
$ 572.00
$ 572.00 - $ 572.00
$ 572.00
$ 458.00
$ 458.00 - $ 458.00
$ 458.00

Foster BL4404, 3/8" Industrial Coupler x 1/2" Female NPT, 4 Series, Ball Lock, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster BL4404 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
$ 458.00
$ 458.00 - $ 458.00
$ 458.00
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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 %
$ 483.00
$ 483.00 - $ 483.00
$ 483.00
$ 386.00
$ 386.00 - $ 386.00
$ 386.00

Foster 4404, 3/8" Industrial Coupler x 1/2" Female NPT, 4 Series, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 4404 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series — a...

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$ 483.00
$ 483.00 - $ 483.00
$ 483.00
$ 386.00
$ 386.00 - $ 386.00
$ 386.00
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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 %
$ 508.00
$ 508.00 - $ 508.00
$ 508.00
$ 407.00
$ 407.00 - $ 407.00
$ 407.00

Foster 4204W, 3/8" Industrial Coupler x 3/8" Female NPT, 4 Series, Water, Brass/SS

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 4204W is a Brass/SS 3/8" industrial coupler from the Foster 4 Series — a h...

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$ 508.00
$ 508.00 - $ 508.00
$ 508.00
$ 407.00
$ 407.00 - $ 407.00
$ 407.00
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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 %
$ 894.00
$ 894.00 - $ 894.00
$ 894.00
$ 715.00
$ 715.00 - $ 715.00
$ 715.00

Foster BL4204S/S, 3/8" Industrial Coupler x 3/8" Female NPT, 4 Series, Ball Lock, 303 Stainless

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster BL4204S/S is a 303 Stainless 3/8" industrial coupler from the Foster 4 Ser...

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$ 894.00
$ 894.00 - $ 894.00
$ 894.00
$ 715.00
$ 715.00 - $ 715.00
$ 715.00
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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 %
$ 842.00
$ 842.00 - $ 842.00
$ 842.00
$ 674.00
$ 674.00 - $ 674.00
$ 674.00

Foster 4204S/S, 3/8" Industrial Coupler x 3/8" Female NPT, 4 Series, 303 Stainless

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 4204S/S is a 303 Stainless 3/8" industrial coupler from the Foster 4 Serie...

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$ 842.00
$ 842.00 - $ 842.00
$ 842.00
$ 674.00
$ 674.00 - $ 674.00
$ 674.00
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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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$ 520.00
$ 520.00 - $ 520.00
$ 520.00
$ 415.00
$ 415.00 - $ 415.00
$ 415.00

Foster 4204S, 3/8" Industrial Coupler x 3/8" Female NPT, 4 Series, Steam/EPDM, Brass body, Brass sleeve, SS valve

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 4204S is a Brass body, Brass sleeve, SS valve 3/8" industrial coupler from...

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$ 520.00
$ 520.00 - $ 520.00
$ 520.00
$ 415.00
$ 415.00 - $ 415.00
$ 415.00
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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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$ 501.00
$ 501.00 - $ 501.00
$ 501.00
$ 402.00
$ 402.00 - $ 402.00
$ 402.00

Foster 4204H, 3/8" Industrial Coupler x 3/8" Female NPT, 4 Series, Heat/Viton, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 4204H is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series — ...

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$ 501.00
$ 501.00 - $ 501.00
$ 501.00
$ 402.00
$ 402.00 - $ 402.00
$ 402.00
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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 %
$ 498.00
$ 498.00 - $ 498.00
$ 498.00
$ 398.00
$ 398.00 - $ 398.00
$ 398.00

Foster BL4204, 3/8" Industrial Coupler x 3/8" Female NPT, 4 Series, Ball Lock, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster BL4204 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series —...

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$ 498.00
$ 498.00 - $ 498.00
$ 498.00
$ 398.00
$ 398.00 - $ 398.00
$ 398.00
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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 %
$ 417.00
$ 417.00 - $ 417.00
$ 417.00
$ 334.00
$ 334.00 - $ 334.00
$ 334.00

Foster 4204, 3/8" Industrial Coupler x 3/8" Female NPT, 4 Series, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 4204 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series — a...

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$ 417.00
$ 417.00 - $ 417.00
$ 417.00
$ 334.00
$ 334.00 - $ 334.00
$ 334.00
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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$ 484.00
$ 484.00 - $ 484.00
$ 484.00
$ 388.00
$ 388.00 - $ 388.00
$ 388.00

Foster BL4004, 3/8" Industrial Coupler x 1/4" Female NPT, 4 Series, Ball Lock, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster BL4004 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series —...

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$ 484.00
$ 484.00 - $ 484.00
$ 484.00
$ 388.00
$ 388.00 - $ 388.00
$ 388.00
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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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$ 403.00
$ 403.00 - $ 403.00
$ 403.00
$ 324.00
$ 324.00 - $ 324.00
$ 324.00

Foster 4004, 3/8" Industrial Coupler x 1/4" Female NPT, 4 Series, Brass/Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 4004 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series — a...

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$ 403.00
$ 403.00 - $ 403.00
$ 403.00
$ 324.00
$ 324.00 - $ 324.00
$ 324.00
Save 20% Save %

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