Check-Mate's OEM line of 2011 style magazines is made from the highest quality American-milled stainless steel magazine tube with a polymer follower and base pad. Every tube is through-hardened for exceptional strength and durability. Tubes are polished inside and out to eliminate drag. The follower is designed featuring Check-Mates anti-friction, self-lubricating polymer for exceptional feed and function with every round. Check-Mates high-performance springs offer high quality, outstanding reliability, and exceptional spring endurance.