Made of 420 Stainless Steel that gives a great resistant to corrosion; very long lasting due to the greater strength given by the heat treatment. Polish inside to ensure an easy and smooth tube loading; feeding and performance that exceed all expectations. Fits 2011 Pistols The spring/follower and aluminum base pad was designed to maximize capacity and realiability but fitting into the IPSC Standard Division measuring box. Capacity: c/38/9 – 20+1rds.; 40S&W-18+1rds; 45acp – 13+1rds. This magazine doesn’t stop the Slide back when empty.