The Agency Arms Field Slide with Agency Optics System (AOS) 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. These pre-cut slides will come with a ISMI Recoil Spring Assembly and a Channel Liner installed (not included on the G43 compatible slides). They have been machined from 17-4 Stainless Steel and have been refinished in Diamond Like Carbon (DLC). DISCLAIMER: This product is not manufactured, authorized, endorsed, or warranted by GLOCK. GLOCK does not warrant or represent that this product is compatible with GLOCK pistols.