Still diving with that old regulator? Did your 3/8" pressure gauge hose die and you can't find a 3/8" replacement hose? Don't retire your trusted pal just because all pressure gauges now have 7/16" hoses. This adapter is just the item you need to prolong the life of your trusty old regulator. Adapter has 3/8" male threaded end that will fit your older model First-Stage with 7/16" female to accept the new HP hose standard. Adapter is made of marine chrome plated brass for strength and durability and comes with standard hose O-ring so it's ready for installation.