BCP Adjustable Watch Back Case Cover Remover Opener Wrench Repair Change Battery Tool for Waterproof/Large Watches crab tool adjusts from approx. 15 mm to 52mm to open watches with backs that screw off Size :70mm X 28mm X 11mm,  Tips adjust from 7/16" to 2 1/8" (11 mm to 54 mm). Has adjustable tempered pins for easy use on water resistant cases. Its compact size makes it very convenient