Water Gremlin developed the Rubbercor® Sinker in 1949... the first truly original idea in sinkers since the rock. Rubbercor® slips easily on and off your line. Just give the rubber ears a half twist in opposite directions and Rubbercor® is ready to take your bait down to where the fish are biting. Your line is protected by the rubber core inside the lead sleeve. To remove simply twist the ears back to their original positions. There's no tying no pinching no fuss no mess. Rubbercor® is safe to use even on the lightest monofilament line.