MULTI-PURPOSE, ALL SEASON BITE ALERT! ATTACHES TO ROD OR TIP-UP, & RUNS ON 2 - 1.5V BUTTON BATTERIES, INCLUDED. PLACE LINE THROUGH THE METAL CLIP AND TUBE, WHEN THE FISH PULLS OUT THE LINE, THE CLIP MAKES CONTACT - SOUNDS THE ALARM AND TURNS ON THE RED LIGHT. APPROX. 2-1/4" X 1/2".