0.5 LPM valve most widely used in the industry. 1500 lpm display, male threads for 34,58,116 Liter aluminum cylinders. Also good for 103 Liter steel cylinder which takes male thread. 1500 LPM good for newer high pressure cylinders.
Do not buy for:
Steel cylinders 17,34 liter, they use a female valve which fits over bottle threads like propane torch bottles.