The TTI 4mm magazine extension is a mid-profile base pad designed for 2011 style magazines in 9mm/38 Super calibers. This precision extension increases capacity by +2 rounds (20 to 22 rounds) while maintaining USPSA 140mm gauge compliance.TTI 2011 Style Magazine Base Pad Extension4mm mid-profile design for optimal performance+2 round capacity increase with factory spring and followerCompatible with Staccato/Infinity/Springfield Prodigy/Atlas magazinesRecommended for 140mm magazinesFits USPSA 140mm gauge for competition useHard coat anodized red finishIdeal for competitive shooters and enthusiasts looking to maximize magazine capacity while maintaining regulatory compliance for USPSA competition shooting.