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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 %
$ 588.00
$ 588.00 - $ 588.00
$ 588.00
$ 471.00
$ 471.00 - $ 471.00
$ 471.00

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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$ 588.00
$ 588.00 - $ 588.00
$ 588.00
$ 471.00
$ 471.00 - $ 471.00
$ 471.00
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 %
$ 496.00
$ 496.00 - $ 496.00
$ 496.00
$ 397.00
$ 397.00 - $ 397.00
$ 397.00

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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$ 496.00
$ 496.00 - $ 496.00
$ 496.00
$ 397.00
$ 397.00 - $ 397.00
$ 397.00
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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 %
$ 522.00
$ 522.00 - $ 522.00
$ 522.00
$ 418.00
$ 418.00 - $ 418.00
$ 418.00

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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$ 522.00
$ 522.00 - $ 522.00
$ 522.00
$ 418.00
$ 418.00 - $ 418.00
$ 418.00
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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 %
$ 919.00
$ 919.00 - $ 919.00
$ 919.00
$ 735.00
$ 735.00 - $ 735.00
$ 735.00

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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$ 919.00
$ 919.00 - $ 919.00
$ 919.00
$ 735.00
$ 735.00 - $ 735.00
$ 735.00
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 %
$ 866.00
$ 866.00 - $ 866.00
$ 866.00
$ 692.00
$ 692.00 - $ 692.00
$ 692.00

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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$ 866.00
$ 866.00 - $ 866.00
$ 866.00
$ 692.00
$ 692.00 - $ 692.00
$ 692.00
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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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$ 535.00
$ 535.00 - $ 535.00
$ 535.00
$ 427.00
$ 427.00 - $ 427.00
$ 427.00

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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$ 535.00
$ 535.00 - $ 535.00
$ 535.00
$ 427.00
$ 427.00 - $ 427.00
$ 427.00
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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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$ 515.00
$ 515.00 - $ 515.00
$ 515.00
$ 413.00
$ 413.00 - $ 413.00
$ 413.00

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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$ 515.00
$ 515.00 - $ 515.00
$ 515.00
$ 413.00
$ 413.00 - $ 413.00
$ 413.00
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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 %
$ 512.00
$ 512.00 - $ 512.00
$ 512.00
$ 409.00
$ 409.00 - $ 409.00
$ 409.00

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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$ 512.00
$ 512.00 - $ 512.00
$ 512.00
$ 409.00
$ 409.00 - $ 409.00
$ 409.00
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 %
$ 429.00
$ 429.00 - $ 429.00
$ 429.00
$ 344.00
$ 344.00 - $ 344.00
$ 344.00

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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$ 429.00
$ 429.00 - $ 429.00
$ 429.00
$ 344.00
$ 344.00 - $ 344.00
$ 344.00
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 %
$ 498.00
$ 498.00 - $ 498.00
$ 498.00
$ 398.00
$ 398.00 - $ 398.00
$ 398.00

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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$ 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
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$ 414.00
$ 414.00 - $ 414.00
$ 414.00
$ 333.00
$ 333.00 - $ 333.00
$ 333.00

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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$ 414.00
$ 414.00 - $ 414.00
$ 414.00
$ 333.00
$ 333.00 - $ 333.00
$ 333.00
Save 20% Save %

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