Adjustable Rear Sight (new style - does not extend over back of slide) - Fits All models except 42, 43 - Gen3 & Gen4 (BOTH). DISCLAIMER: “GLOCK” is a federally registered trademark of GLOCK, Inc. and is one of many trademarks owned by GLOCK, Inc. or Glock®Ges.m.b.H. Neither Brownells 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 genuine GLOCK, Inc. and Glock®Ges.m.b.H. products and parts visit www.Glock®.com.