Fits Gen 1-3 Glock 23 compatible frames. This complete Remsport bullnose upper delivers Gen 5-inspired styling on Gen 3 geometry - drops on, no gunsmithing, no fitting. Finish is matte black nitride on both slide and barrel for corrosion resistance and reduced wear through cycling. Features: Remsport iron sight-cut bullnose slide, black nitride finished .40 S&W black nitride barrel, drop-in fit 3CR Tactical slide completion kit installed - all internals Standard-height polymer sights installed and aligned Fully assembled and function-tested - no gunsmithing required Lube all contact surfaces before first use and run 200 rounds of standard .40 S&W ammunition during break-in before moving to duty loads. Confirm your lower is a Gen 1-3 Glock 23 pattern - this upper will not fit Gen 4 or Gen 5 frames. DISCLAIMER: "GLOCK" is a federally registered trademark of GLOCK, Inc. and is one of many trademarks owned by GLOCK, Inc. and GLOCK Ges.m.b.H. Neither 3CR Tactical nor this site are affiliated in any manner with, or otherwise endorsed by, GLOCK, Inc. or GLOCK Ges.m.b.H. The use of "GLOCK" on this page is merely to advertise the sale of GLOCK pistols, parts, or components. For additional genuine GLOCK, Inc. and GLOCK Ges.m.b.H products and parts visit www.glock.com.