LaserMax LMS1151G Guide Rod Laser 5mW Green Laser with 520nM Wavelength, 20 yds Day/300 yds Night Range & Made of Aluminum for Glock 20, 21, 41 Gen1-3Designed specifically for use in Glock 20 (Gen4), Glock 21 (Gen4), and Glock 41 (Gen4) pistols, the...