This is a Crimson Trace Corporation Laserguard known as the Laserguard Pro, model LL-803.
LL-803 Laserguard(R) Pro for GLOCK(R) GLOCK(R) G42" G43" G43X and G48 is a powerful red laser sight and 150 Lumen LED white light in a single compact unit. Designed specifically for these compact platforms" this illumination and targeting product is activated with Crimson Trace's famed Instinctive Activation(TM)" which activates the unit with a normal firing grip. LL-801 offers four modes of operation: Laser + Light" Laser Only" Light Only" and Laser + Light Strobe. The unit features a Master On/Off Switch" is completely user-installed in moments" and is adjustable for windage and elevation.
Features:
Front activation
Red laser
Factory sighted at 50Ft
.5 inch diameter at 50 feet