Features: Maximum open diameter of 55mm, minimum open diameter of 14mm. Specially designed for opening and closing the back cover with concave and notch embedded back cover watch. Made of quality metal and plastic material, durable and suitable for all types of watch. Light in weight makes it easy to carry with you. Suitable for watch makers and watch repairing workers. Specifications: Condition: 100% Brand New Material: Metal + plastic Total Length: Approx. 18cm / 7.1in Maximum open diameter: 55mm / 2.2in Minimum open diameter: 14mm / 0.6in Weight: 138 g / 4.9 oz(approx.) Usage: adjust the two steel die of the watch opener to the appropriate position, choose the shape of the back cover of your watch, put it on the back cover of the watch, and then use your hand to hold the top of the watch opener, rotate to the left, the bottom cover can be opened. Package List: 1 x Watch Case Opener 4 x Dies . Note: Please note that the new type and old type of this product will be sent randomly, and make sure you will not mind before ordering.