The Villain Weapon Systems GL4 External Focusing Lens addresses the wide flood pattern of the GL4's IR illuminator and focuses the 300mW beam into a tight spot capable of clearly illuminating your target past 100m. The focusing lens also eliminates the "washout" associated with the close-distance foreground flood illumination of the standard IR illuminator. The GL4 Pro EFL gives two illuminator patterns selectable via an included spacer that can be added or removed during the Lens installation: A square pattern that focuses all of IR LED output (the IR illuminator is a square-shaped LED - thus the square pattern) A more rounded pattern that is slightly-less focused but more familiar to most users As the EFL is designed to extend the long-range performance of the GL4 Pro for rifles and PCCs, EFL-equipped GL4 Pros may not be compatible with pistol holsters previously compatible with the GL4 and XVL2. Holster modifications may be required. Check out 4MR Ranch's Review of the EFL Here!Comapatible with the RovyVon GL4 Pro, GL4 Pro XL, and GL4 Pro FP. NOT compatible with the XVL2 or Standard/IR GL4 A Cold Harbour Supply Exclusive Product. 100% Designed and Made in the USA by Villain Weapon SystemsGL4-Pro not included, to buy this as a package check out this page: HERE