The Glock 21 Gen4 SF combines Short Frame grip reduction with all Gen4 improvements — MBS system, dual recoil spring, and RTF4 grip texture — on the full-size .45 ACP platform. The SF/Gen4 combination was the first to offer both ergonomic grip customization through MBS and the base SF trigger-reach reduction, making the G21 accessible to the widest range of hand sizes. Type: Pistol Action: Semi-Automatic Caliber: .45 ACP Capacity: 13 Year introduced: 2013, Austria Weight: 26.28 oz Overall length: 8.22" Status: Active Intended use: Law Enforcement, Self-Defense