Calculates muzzle velocity (FPS/MPS) and ROF (RPM). Compatible with 14mm negative threading patterns. Quality digital display with brightness controls. Power saving, standby, and auto-power off modes. Programmable BB counter to count up or down. Battery level monitoring and low ammo warning. Programmable burst control unit. (2-10 burst / full auto) PEQ control box mounts to any 20mm tactical rails. Communicates via wireless signal. (SCU 8 channel memory) In the Box 1X Tracer 1X PEQ Box with LED display Specifications: Material Metal/Polymer Muzzle Velocity Range 30-400+ M/S (90-1200+ FPS) R.O.F. Range 100-6000 RPM Muzzle Energy Range 0.01-9999 Joule Power Tracer (4X AAA Batteries) PEQ Box (2X AA Batteries) (Batteries not included) California Proposition 65 Warning: Cancer and Reproductive Harm - www.P65Warnings.ca.gov