The Field edition has no windows and is designed for the utilitarian shooter. It features several enhancements without introducing windows. *Slide Serration count will change depending on the length of the slide. Includes Agency Optic System (AOS) cutout. Separate adapter plates needed for specific RDS mounting. These pre-cut slides will come stripped with a ISMI Recoil Spring Assembly and a Channel Liner installed They have been machined from 17-4 Stainless Steel and have been refinished in Diamond Like Carbon (DLC). ""GLOCK A(R) ","Gen 3", "Gen 4", and "G17" - "G43" are several federallyregistered trademarks of many owned by Glock, Inc. or Glock Ges.m.b.H. Agency Arms isnot affiliated with or endorsed by Glock, Inc. or Glock Ges.m.b.H."