This is the M72 LAAW Rocket Aiming Laser from Crimson Trace Defense.
Developed in conjunction with Nammo Talley, the Rocket Aiming Laser has been found to increase hit probability from 18% to over 80% in low light conditions. Available in visible red, green or IR visible, the device can be installed on existing M72s by the user, or installed new from Nammo Talley.
www.crimsontrace.com/ctc-defense