The Foxtail Precision 100013 is designed as an optics mounting adapter suitable for non-MOS Glock, including RMR, SRO, along with Holosun models 407c, 507c, 508t. It is composed of robust 7075 Aluminum to ensure durable service.In a distinct design feature that replaces the rear sight, it offers ease and convenience in fullscreen sight mounting applications. The package also includes Mounting Screws for a complete and straightforward installation procedure.