THESE QUICK DETACHABLE RINGS FIT, CZ550, BRNO ZG47 AND 21H, ZKK 600 SERIES * SIMPLE ¼ TURN LOCK OR RELEASE * RETURN TO ZERO * LIFE TIME WARRANTY * MACHINED FROM SOLID BAR STOCK * HEAT TREATED FOR A LIFETIME OF HARD USE * MANUFACTURED ON HIGH PRECISION COMPUTER NUMERICAL CONTROLED MACHINES * MANUFACTURED ENTIRELY IN THE U.S.A.