Screwback Watch Case Wrench. CWR770. Like the famous Jaxa CO790.
Modeled after the famous Swiss Bergeon Jaxa Design which cost $60.00. This economical 3-prong case wrench does the complete job. Works on watches with screw backs or the so called waterproof cases; allign post in notches on back and unscrew. Very simple to use on most screw back watches. Sturdy wood box, foam lined inside top, with brass metal latches. Dimensions: 7 inches long x 3.75 wide x 3.25 height. One year factory warranty. Some cases look like or seem like a screwback but fake out the consumer with a snapback to appear more expensive. Call the place you bought it and ask them before you do anything.
Make sure you know what you have. If you have a satin pillow elite watch like Rolex or Cartier don't try opening it yourself to save a buck, take it to a watchmaker.