The TTI 4mm Magazine Extension is a mid-profile basepad designed for 2011 style magazines in 9mm/38 caliber. This +2 round extension increases capacity from 20 to 22 rounds while maintaining USPSA 140mm gauge compliance.TTI 4mm Mid-Profile Magazine ExtensionCompatible with Staccato Infinity Springfield Prodigy Atlas 2011 magazines+2 round capacity increase with factory spring and followerRecommended for 140mm magazinesFits USPSA 140mm gauge specificationsBlue anodized finishIdeal for competitive shooters seeking increased capacity while maintaining equipment compliance for USPSA competition use.