that's the valve off of a Worrgas adjustable HPA tank. The HP is for the fill nipple, the LP is the output. Has a pretty good adjustment range, on mine I've ran it as lose as 300psi for my bushmaster, to as high as 1200 psi for x-valved mag (the mag got VERY reactive at that pressure). They weren't known for their reliability, mine had to be sent back twice due to a dirty reg seat when it was brand new, but when they worked they worked pretty well. That particular one has a busted off on/off knob (the metal cone it a guard for the knob).
Nunquam emere quid potes facere