1/2″ PEX × 3/8″ Straight Stop Valve — Quarter-Turn Chrome Shut-Off

A supply stop is the valve you're glad exists the day a faucet needs pulling — one quarter-turn and the fixture is isolated while the rest of the house keeps its water. This straight stop bridges a 1/2″ PEX rough-in coming up out of the floor to the 3/8″ compression riser that feeds a faucet, toilet, or dishwasher, so the run goes straight up with no angle. The PEX inlet crimps on with a copper ring or stainless clamp; the 3/8″ compression outlet tightens onto a standard flexible supply with just a nut and ferrule. Inside is a quarter-turn ball rather than an old multi-turn washer stem, so it seats positively every time and won't seize half-open after years untouched. The body is lead-free brass under polished chrome, clean enough to leave exposed under a pedestal sink or open vanity. It's the small part that turns a fixture swap into a five-minute job instead of a trip to shut off the main.