This is a new Jaxa jumbo wrench large watch case back openers, the perfect tool for screw type watches specially for water resistant watches, It includes 4 different types of grip heads or pins to fit all varieties of watch case back designs. A Jaxa style watch case opener suitable for large case back diameters Can open diameters between 19mm to 60mm Includes small ruler and 12 pins A handy tool for watchmakers and watch repairers to open the back of large watches