New Rolex Watch Back Remover. This waterproof watch case closer and opener is especially designed for waterproof Rolex oyster cases. Accurately interlocks with the knurled edges of genuine Rolex case backs. It will not slip or damage case backs. There are a variety of dies and sizes. You receive: One die measuring 18.5 mm in diameter. One die measuring 20.5 mm in diameter. One die measuring 22.5 mm in diameter. One die measuring 26.5 mm in diameter. One die measuring 28.5 mm in diameter. One die measuring 29.5 mm in diameter.