Keyless Classi-Lock with reverse lock works on CNC mills where drills must be changed quickly on spindles with quick-braking action. Locking mechanism ensures that chuck won't open if spindle suddenly stops, even in reverse motion. Quick drill-change minimizes downtime; user simply rotates locking ring to open position, opens drill chuck, replaces old drill with new drill, tightens chuck, and rotates ring to locked position. Chucks are available in 5 models with steel jaws, and 2 models with diamond-coated jaws for holding carbide and hardened-shank drills.