The Zaffiri Precision Upper Parts Kit (UPK) is built for the Glock 19 Gen 5 and is used to finish a custom or stripped Gen 5 slide. If you bought a bare Glock 19 Gen 5 slide, this kit supplies the internal slide parts that turn it into a working upper. All parts come from a US manufacturer and are made to the original specification, so they drop in the way the factory parts do. These parts are Gen 5 specific. They are not compatible with Gen 3 or Gen 4 slides, and they will not fit other Glock models. Features: Upper parts kit for the Glock 19 Gen 5 Finishes a custom or stripped Gen 5 slide Parts from a US manufacturer Made to the original specification Gen 5 specific; not compatible with other generations Confirm that your slide is a Glock 19 Gen 5 pattern before you order. A barrel and recoil spring assembly are sold separately. After you assemble the slide, do a full function check: trigger reset, firing pin safety and slide-to-frame fit, before live fire. 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.