Perst-4 is used to point targets when observing, inspecting and watching small arms shooting at night. This product is a small optical mechanical device that forms laser radiation flux. This product is installed on Picatinny rails. The KV-D2 Tactical swtich (in the kit)can be installed on picatinny rails and 1913 rails. Perst-4 contains 2 laser functions:Green Laser light source: wavelength – 532 nm/IR light source: wavelength – 850 nm. Green Laser light source: wavelength – 532 nm? IR light source: wavelength – 850 nm? Power supply: CR123A (Not included) / battery (3 V). (Product does not include battery). Effective range in the dark:Green beam: 500 ± 100 m. IR beam: 400 ± 100 m. 91 ± 3 mm. Fit For: 20mm Picatinny Rail? Material: Metal Special Note:? The triangular area on the host can switch between visible laser and IR? On the top or side of the host, the round switch is turned on. Turn on through the KV-1P Wire Control Switch? Press the swtich quickly to realize the strobe function? Two small circular buttons on the main unit to adjuest the laser brightness. 1Tactical laser light Notes:? Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 3 mm.