Full metal high quality version. Fit For: 20mm Picatinny Rail. 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-5PU Tactical swtich (in the kit)can be installed on picatinny rails and 1913 rails. Perst-4 contains 2 laser functions. Green VIS laser source: wavelength – 635 nm. IR laser source: wavelength – 850 nm. Battery type: 1 CR123A battery (3v / 3.7v). Effective range in the dark. VIS Green Laser beam: 300 ± 100 m. IR laser beam: 400 ± 100 m. Overall dimensions: (37? 60? 91) ± 3 mm. 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-5PU Wire Control Switch. Two small circular buttons on the main unit to adjuest the laser brightness.