Athlon makes ballistic calculations easy with the Athlon 707301 Rangecraft Velocity Pro Radar Chronograph. It picks up the projectiles via Doppler radar, thus eliminating the need to mount the Rangecraft Velocity Pro to the weapon. This means it won't affect your zeroing or barrel harmonics, so your accuracy remains the same. Since the unit isn't triggered by a muzzle blast, it can pick up on projectiles from firearms with suppressors, muzzle breaks, compensators, and other muzzle devices.Features :65-5,000FPS".17-50" Diameter"6+ Hour Battery Life"2.4" Display"