Crosman. Have a part # and, credit / debit card ready. That's where I got the last one, to replace, for a customer.
After a little digging,, Crosman gauges apparently are 1/8" npt.
Just Google it. There's a buttload under 20 bucks.
I new they were metric just not sure of size so I got both m10 and m8 same type on the avenger and on my GX-cs2 they glow in the dark Amazon linkI picked the 40mpa