Die Sizes (mm): 18.50, 20.20, 22.50, 26.50, 28.30, 29.50.
To open oyster style watches. Watch gets locked into position so that it reduces the chances of scratching.
Butterfly Type with Centre Screw.
Adjustable metal pin will slide to open many screw-on watch case backs. Popularly used in Bulova watches. Maximum opening: 50mm.