Punch-down block

A punch-down block (also punchdown block, punch block, punchblock, quick-connect block and other variations) is a type of electrical connection often used in telephony. It is named because the solid copper wires are "punched down" into short open-ended slots which are a type of insulation-displacement connectors. These slots, usually cut crosswise (not lengthwise) across an insulating plastic bar, contain two sharp metal blades which cut through the wire's insulation as it is punched down. These blades hold the wire in position and make the electrical contact with the wire as well.