Kalevel 2pcs DIY Home Car Stereo 2-Way Speaker Box Terminal Round Square Spring Cup Connector Binding Post Banana Jack and Plugs Subwoofer Plugs 93x80mm (Black) Pack of 2pcs speaker terminal spring cup connectors Material: durable plastic, copper and gold-plated metal. Spring terminals ensure a tight and secure connection. Overall diameter : about 93mmx80mm (3.7"x3.2"); Cutout diameter: about 66mm (2.6"); Top-mount depth: 20mm (0.8"). Rear connections use quick disconnect connectors. Positive (Red) and negative (Black) indicators to ensure proper wiring.