New Jaxa opening wrench is made large to work with newly larger watches that cannot be opened with regular size wrenches. This jaxa comes with 4 different teeth for different watch casebacks. The wrench can be used for changing watch batteries, movements and more. The tool includes 4 sets of interchangeable pins: round, flat, toothed and square designed to open various types of watches. Twist handle adjusts to the size of the watch caseback. Can open watch backs from 18mm-62mm. Tool measures 6 1/2 x 2 7/8 x 3 /4 and can be stored away easily.