From the Manufacturer
OPW 7H Automatic Shut-Off Nozzles
If you operate a full-service truck stop, refuel your own fleet or manage a card lock refueling location, the low cost, long life and durability of the OPW 7H high flow nozzle can h help increase your productivity, sales and profits. The OPW 7HB will not open until the pumping system is pressurized, and closes automatically when the pressure is removed.