Foster H3B-103, 3/8" ISO-B Hydraulic Coupler x 3/8" Female NPT, ISO-B Series, EPDM Seal, Brass

Product Details

The most widely used industrial hydraulic quick coupling, compatible with ISO 7241-1 Series B. The Foster H3B-103 is a brass 3/8" coupler in the FHK Series, which interchanges with Breco DS and other ISO-B couplings on hydraulic tools, machinery, and equipment. Two-way shut-off, rated to 2200 PSI. (Also known as the FHK Series.)

Why this coupler

• ISO-B interchange — couples with any ISO 7241-1 Series B half of the same body size, the most common hydraulic standard.
• Two-way shut-off — both halves seal on disconnect, preventing fluid loss and air inclusion.
• Brass body — rated to 2200 PSI with a 4:1 safety factor per ANSI/B93.2.

Frequently asked questions

Are these ISO-B couplers?
Yes — the Foster FHK Series is compatible with ISO 7241-1, Series B, the most widely used industrial hydraulic interchange. It mates with Breco DS and other ISO-B halves of the same body size.

What plug does it take?
Any 3/8 plug on the same ISO-B interface in matching brass, epdm seal. The matching Foster plug is K3B-103.

Can I connect it under pressure?
No. ISO-B couplings connect and disconnect at zero pressure. Relieve system pressure first.

Why buy from hpcouplers: Foster quality, responsive US-based support, accurate specs, fast shipping.

ISO-B Series (ISO 7241-1 Series B / FHK) — Complete Series Chart

The size you are viewing is shown first, with the rest of the series below. Base couplings appear before ball lock and seal options. Dust caps and plugs fit by body size and are labeled by which half they protect. Click any part number to open that product.