Positive lever-locking clamp ensures reliable measurement at all times. Special Features: Unique ratchet design allows one hand operation. .0001" graduations. Accuracy = .0001" Swiss style design, balance and quality. Ratchet thimble assures you of consistent readings at all times. Barrel, thimble and frame are satin chrome finished; microfine graduations allow easy reading. Fully insulated frame isolates heat from the operator's hand.