The TTI 4mm Base Pad is a mid-profile magazine extension designed for 2011 style magazines in 9mm and 38 Super calibers featuring a premium gold finish and +2 round capacity increase.TTI 2011 Magazine Base Pad Extension4mm mid-profile design+2 round capacity with factory spring and followerCompatible with Staccato Infinity Springfield Prodigy and Atlas magazinesRecommended for 140mm magazinesUSPSA 140mm gauge compliantHard coat anodized gold finishIdeal for competitive shooters and enthusiasts seeking increased capacity while maintaining USPSA compliance this extension works with your existing factory components for reliable performance.