Optic-Ready; Cycles 1.75″, 2.75″ or 3″ shells interchangeably; Compact and Adjustable Length of Pull (12″-13″); No need for mini shell adaptor; Redesigned Elevator, Bolt Slide and a new Energy-Absorbing Bumper; Standard features include dual extractors, twin action bars, steel-to-steel lockup and ambidextrous safety