This is a Crimson Trace Corporation LaserGrip known as the Lasergrips, model LG-404.
The flagship LG-404 is Crimson Trace's most popular 1911 laser sight model for Officer's" Compact and Defender variants. Featuring rugged polymer side panels and a rubber-overmold activation button" these are the recommended Lasergrips(R) for most 1911 shooters. Standard to Crimson Trace(R) Lasergrips" the LG-404 features instinctive activation. This means that the laser sight automatically springs to life when the weapon is held in a natural firing grip. This product is not compatible with ambidextrous safety levers.
Features:
Pressure activation
Red laser
Factory sighted at 50Ft
.5 inch diameter at 50 feet