4 Position gas plug for the SIG 553 (SB) rifle. Different positions for different calibers are available.
 
GP90 (62gr) Positions: 1.3, 1.4, 1, X
NATO Positions: 1.2, 1.3, 0.9, X
Does fit only 5.56mm SIG 553 rifles
 
Made in Switzerland by SAN SWISS ARMS.