"Independent" means that each jaw moves independently. Such 4-Jaw Chucks are used for holding odd shaped pieces or where zero tolerance is required. This 10" 4-jaw chuck with a 2-1/2" bore has semi-steel bodies and hardened reversible jaws. Requires a mounting plate. Note the mounting holes through the back of the chuck. This is because each jaw moves independently and there is no scroll in the middle.
