Atlas Gunworks 2011 126mm Slidelock 9mm Magazines! New internal dimensions greatly improves feeding in all double stack 2011's New upper tube dimensions paired with a proper follower makes reliable lockback achievable 9mm tubes work with .38 super and .38 super comp. Designed to work with all modular grip double stacks Lockback capacity 18 Add Grams FKS 11 for capacity of 20 (Lockback tab should be removed from Grams follower) Redesigned, dimensionally correct mag body +18% spring for reliable feed and lockback Premium follower for reliable feed and lockback Discrete premium 4mm basepad Mfg: Atlas Gunworks