Skip to content
Fall Ready Sale15% off everything through Oct 31FALLREADY15Tap to apply at checkout →
15% off through Oct 31FALLREADY15Tap to apply →

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.

Filters

Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
€24,95 - €24,95
€24,95
€24,95 - €24,95
€24,95

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 —...

View full details
€24,95 - €24,95
€24,95
€24,95 - €24,95
€24,95
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
€20,95 - €20,95
€20,95
€20,95 - €20,95
€20,95

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...

View full details
€20,95 - €20,95
€20,95
€20,95 - €20,95
€20,95
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
€21,95 - €21,95
€21,95
€21,95 - €21,95
€21,95

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...

View full details
€21,95 - €21,95
€21,95
€21,95 - €21,95
€21,95
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
€37,95 - €37,95
€37,95
€37,95 - €37,95
€37,95

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...

View full details
€37,95 - €37,95
€37,95
€37,95 - €37,95
€37,95
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
€35,95 - €35,95
€35,95
€35,95 - €35,95
€35,95

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...

View full details
€35,95 - €35,95
€35,95
€35,95 - €35,95
€35,95
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
€22,95 - €22,95
€22,95
€22,95 - €22,95
€22,95

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...

View full details
€22,95 - €22,95
€22,95
€22,95 - €22,95
€22,95
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
€21,95 - €21,95
€21,95
€21,95 - €21,95
€21,95

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 — ...

View full details
€21,95 - €21,95
€21,95
€21,95 - €21,95
€21,95
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
€21,95 - €21,95
€21,95
€21,95 - €21,95
€21,95

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 —...

View full details
€21,95 - €21,95
€21,95
€21,95 - €21,95
€21,95
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
€17,95 - €17,95
€17,95
€17,95 - €17,95
€17,95

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...

View full details
€17,95 - €17,95
€17,95
€17,95 - €17,95
€17,95
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
€20,95 - €20,95
€20,95
€20,95 - €20,95
€20,95

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 —...

View full details
€20,95 - €20,95
€20,95
€20,95 - €20,95
€20,95
Foster BLH1B, 1/8" ISO-B Hydraulic Coupler x 1/8" Female NPT, ISO-B Series, Ball Lock, Brass
€17,95 - €17,95
€17,95
€17,95 - €17,95
€17,95

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...

View full details
€17,95 - €17,95
€17,95
€17,95 - €17,95
€17,95

Request a Quote

Bulk and dealer pricing. Tell us what you need and we’ll reply within one business day.