Adjustable Watch Opener Back Case Tool Press Closer Remover Wrench Watch Battery Remover Screw Wrench Repair Watchmaker Tools This is a case opener for waterproof watches. Tips can adjust from 13mm to 56mm which can fit different size watch cases. Compact and small size, makes it very convenient to carry.  Features: Minimize the risk of slipping and scratching. Water resistant and will not easily get rust or damaged. Tips can adjust from 10mm to 50mm to fit different size watch cases.  Compact and small size, makes it very convenient to carry.  Great for waterproof watch case opening, batteries replacing and watch repairing. Specifications: Material: stainless steel/ABS Type optional: 2 kinds optional Item weight: 45g / 1.59ounces Package weight: 80g / 2.82ounces Item size: 70 * 40 *15mm / 2.76 * 1.18 * 0.59in Package size: 80 * 50 * 20mm / 3.15 * 1.97 * .79in How e: Turn the black knob and make it fit snugly around the watch face plate.  Then roll the adjustment wheel of the watch back case opener to set the bit spacing to fit your watch's back case grooves. Just turn it and your watch back case is open up. Package List: 1 * Watch Back Case Opener