Designed from ground-up. Imperveous to elements. Strong magazine tube virtually eliminates feed lip cracking tube spread & cracking & general fatigue. Manufactured w/proprietary custom designed welding process followed by proprietary multi-step tumbling & finishing process. Follower & base pad design combines advanced manufacturing technology & absolutely precise dimension control assures positive slide-lock after last round had been fored. Follower design w/extended skirt ensures stability in operation minimizes creep from tube when magazine is empty. Seats & locks in weapon w/slide down-fully loaded. Almost indestructable base pad. Numbers 1-10 included on bottom surface of base pad make it easy to mark & identify individual magazines to track usage & performance. Observation ports clearly labeled for rounds 2 through 8 on both sides of magazine-see how many rounds remain. Lifetime Service policy.