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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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$ 96.00
$ 96.00 - $ 96.00
$ 96.00
$ 76.00
$ 76.00 - $ 76.00
$ 76.00

Foster 40-4, 4 Series, Industrial Plug, 1/4" Male NPT, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 40-4 is a Steel 3/8" industrial plug from the Foster 4 Series — a high-flo...

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$ 96.00
$ 96.00 - $ 96.00
$ 96.00
$ 76.00
$ 76.00 - $ 76.00
$ 76.00
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$ 567.00
$ 567.00 - $ 567.00
$ 567.00
$ 453.00
$ 453.00 - $ 453.00
$ 453.00

Foster FM4204, 4 Series, Industrial Coupler, Automatic, 3/8" Female NPT, 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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$ 119.00
$ 119.00 - $ 119.00
$ 119.00
$ 96.00
$ 96.00 - $ 96.00
$ 96.00

Foster 43-4, 4 Series, Industrial Plug, 3/8" Female NPT, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 43-4 is a Steel 3/8" industrial plug from the Foster 4 Series — a high-flo...

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$ 119.00
$ 119.00 - $ 119.00
$ 119.00
$ 96.00
$ 96.00 - $ 96.00
$ 96.00
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$ 567.00
$ 567.00 - $ 567.00
$ 567.00
$ 453.00
$ 453.00 - $ 453.00
$ 453.00

Foster FM4303, 4 Series, Industrial Coupler, Automatic, 3/8" Male NPT, Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster FM4304 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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$ 160.00
$ 160.00 - $ 160.00
$ 160.00
$ 128.00
$ 128.00 - $ 128.00
$ 128.00

Foster 42-4B, 4 Series, Industrial Plug, 3/8" Male NPT, Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 42-4B is a Brass 3/8" industrial plug from the Foster 4 Series — a high-fl...

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$ 160.00
$ 160.00 - $ 160.00
$ 160.00
$ 128.00
$ 128.00 - $ 128.00
$ 128.00
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$ 96.00
$ 96.00 - $ 96.00
$ 96.00
$ 76.00
$ 76.00 - $ 76.00
$ 76.00

Foster 41-4, 4 Series, Industrial Plug, 1/4" Female NPT, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 41-4 is a Steel 3/8" industrial plug from the Foster 4 Series — a high-flo...

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$ 96.00
$ 96.00 - $ 96.00
$ 96.00
$ 76.00
$ 76.00 - $ 76.00
$ 76.00
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$ 567.00
$ 567.00 - $ 567.00
$ 567.00
$ 453.00
$ 453.00 - $ 453.00
$ 453.00

Foster FM4304, 4 Series, Industrial Coupler, Automatic, 3/8" Male NPT, Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster FM4304 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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$ 414.00
$ 414.00 - $ 414.00
$ 414.00
$ 333.00
$ 333.00 - $ 333.00
$ 333.00

Foster 4004, 4 Series, Industrial Coupler, Manual, 1/4" Female NPT, 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
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$ 563.00
$ 563.00 - $ 563.00
$ 563.00
$ 450.00
$ 450.00 - $ 450.00
$ 450.00

Foster FM4004, 4 Series, Industrial Coupler, Automatic, 1/4" Female NPT, 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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$ 429.00
$ 429.00 - $ 429.00
$ 429.00
$ 344.00
$ 344.00 - $ 344.00
$ 344.00

Foster 4204, 4 Series, Industrial Coupler, Manual, 3/8" Female NPT, 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
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$ 581.00
$ 581.00 - $ 581.00
$ 581.00
$ 464.00
$ 464.00 - $ 464.00
$ 464.00

Foster FM4404, 4 Series, Industrial Coupler, Automatic, 1/2" Female NPT, Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster FM4404 is a Brass 3/8" industrial coupler from the Foster 4 Series — a hig...

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$ 581.00
$ 581.00 - $ 581.00
$ 581.00
$ 464.00
$ 464.00 - $ 464.00
$ 464.00
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$ 124.00
$ 124.00 - $ 124.00
$ 124.00
$ 99.00
$ 99.00 - $ 99.00
$ 99.00

Foster 44-4, 4 Series, Industrial Plug, 1/2" Male NPT, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 44-4 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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$ 165.00
$ 165.00 - $ 165.00
$ 165.00
$ 131.00
$ 131.00 - $ 131.00
$ 131.00

Foster 45-4, 4 Series, Industrial Plug, 1/2" Female NPT, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 45-4 is a Steel 3/8" industrial plug from the Foster 4 Series — a high-flo...

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$ 165.00
$ 165.00 - $ 165.00
$ 165.00
$ 131.00
$ 131.00 - $ 131.00
$ 131.00
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$ 581.00
$ 581.00 - $ 581.00
$ 581.00
$ 464.00
$ 464.00 - $ 464.00
$ 464.00

Foster FM4804, 4 Series, Industrial Coupler, Automatic, 3/8" Hose Barb, Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster FM4804 is a Brass 3/8" industrial coupler from the Foster 4 Series — a hig...

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$ 581.00
$ 581.00 - $ 581.00
$ 581.00
$ 464.00
$ 464.00 - $ 464.00
$ 464.00
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$ 175.00
$ 175.00 - $ 175.00
$ 175.00
$ 142.00
$ 142.00 - $ 142.00
$ 142.00

Foster 48-4B, 4 Series, Industrial Plug, 3/8" Hose Barb, Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 48-4B is a Brass 3/8" industrial plug from the Foster 4 Series — a high-fl...

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$ 175.00
$ 175.00 - $ 175.00
$ 175.00
$ 142.00
$ 142.00 - $ 142.00
$ 142.00
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$ 427.00
$ 427.00 - $ 427.00
$ 427.00
$ 342.00
$ 342.00 - $ 342.00
$ 342.00

Foster 4104, 4 Series, Industrial Coupler, Manual, 1/4" Male NPT, Brass, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 4104 is a Brass/Steel 3/8" industrial coupler from the Foster 4 Series — a...

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$ 427.00
$ 427.00 - $ 427.00
$ 427.00
$ 342.00
$ 342.00 - $ 342.00
$ 342.00
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$ 563.00
$ 563.00 - $ 563.00
$ 563.00
$ 450.00
$ 450.00 - $ 450.00
$ 450.00

Foster FM4104, 4 Series, Industrial Coupler, Automatic, 1/4" Male NPT, Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster FM4104 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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$ 616.00
$ 616.00 - $ 616.00
$ 616.00
$ 494.00
$ 494.00 - $ 494.00
$ 494.00

Foster FM1714, 4 Series, Industrial Coupler, Automatic, 3/8" Push-On Hose Barb, Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster FM1714 is a Brass 3/8" industrial coupler from the Foster 4 Series — a hig...

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$ 616.00
$ 616.00 - $ 616.00
$ 616.00
$ 494.00
$ 494.00 - $ 494.00
$ 494.00
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$ 163.00
$ 163.00 - $ 163.00
$ 163.00
$ 129.00
$ 129.00 - $ 129.00
$ 129.00

Foster 40-4B, 4 Series, Industrial Plug, 1/4" Male NPT, Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 40-4B is a Brass 3/8" industrial plug from the Foster 4 Series — a high-fl...

View full details
$ 163.00
$ 163.00 - $ 163.00
$ 163.00
$ 129.00
$ 129.00 - $ 129.00
$ 129.00
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$ 574.00
$ 574.00 - $ 574.00
$ 574.00
$ 459.00
$ 459.00 - $ 459.00
$ 459.00

Foster FM4504, 4 Series, Industrial Coupler, Automatic, 1/2" Male NPT, Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster FM4504 is a Brass 3/8" industrial coupler from the Foster 4 Series — a hig...

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$ 574.00
$ 574.00 - $ 574.00
$ 574.00
$ 459.00
$ 459.00 - $ 459.00
$ 459.00
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$ 496.00
$ 496.00 - $ 496.00
$ 496.00
$ 397.00
$ 397.00 - $ 397.00
$ 397.00

Foster 4404, 4 Series, Industrial Coupler, Manual, 1/2" Female NPT, 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...

View full details
$ 496.00
$ 496.00 - $ 496.00
$ 496.00
$ 397.00
$ 397.00 - $ 397.00
$ 397.00
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$ 496.00
$ 496.00 - $ 496.00
$ 496.00
$ 397.00
$ 397.00 - $ 397.00
$ 397.00

Foster 4504, 4 Series, Industrial Coupler, Manual, 1/2" Male NPT, Brass, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 4504 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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$ 112.00
$ 112.00 - $ 112.00
$ 112.00
$ 89.00
$ 89.00 - $ 89.00
$ 89.00

Foster 48-4, 4 Series, Industrial Plug, 3/8" Hose Barb, Steel

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster 48-4 is a Steel 3/8" industrial plug from the Foster 4 Series — a high-flo...

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$ 112.00
$ 112.00 - $ 112.00
$ 112.00
$ 89.00
$ 89.00 - $ 89.00
$ 89.00
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$ 588.00
$ 588.00 - $ 588.00
$ 588.00
$ 471.00
$ 471.00 - $ 471.00
$ 471.00

Foster FM4904, 4 Series, Industrial Coupler, Automatic, 1/2" Hose Barb, Brass

Reliable, leak-free 3/8" connections for air and fluid lines. The Foster FM4904 is a Brass 3/8" industrial coupler from the Foster 4 Series — a hig...

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