"The Crimson Trace Laserguard Laser Sight activates instinctively with the shooter's finger by simply holding the weapon naturally. The polymer laser sight attaches to the weapon's triggerguard with no alterations, and are factory sighted for 50', though they are user adjustable for both windage and elevation. When activated, the Crimson Trace Laserguard sends out a 5mW laser dot that can be seen in bright daylight as well as in total darkness. The diameter of the dot is approximately 1/2"" at 50', allowing for precise shot placement. With no front and rear sights to align, laser sights are incredibly fast to acquire, enabling you to place shots on target in stressful, personal defense situations. A small master ""on-off"" switch prevents inadvertently activating the laser when it is not wanted. The Crimson Trace Laserguard Laser Sight runs on one 1/3N Lithium or two 357 silver oxide batteries (included). Instinctive front activation Provide rapid sight acquisition Bright, easily seen dotday or night Adjustable for windage and elevation Master on-off switch Easy to install"