Williams Dual Density Closed Toe RubberWilliams Dual Density Closed Toe Rubber It's a classic tale. You haven't skied in years and get the old slalom ski out of the shed only to discover the rubbers have dried up, cracked and split! This closed toe rubber is perfect for replacing those old rubbers and will keep your old waterski going for years to come. Dual density neoprene lined rubber is comfortable and easy to get on and off.