This Horotec Automatic Watch Case Opener is for snap-on watch case backs. It comes supplied with 3 shaped tips: 3.5mm, 4.5mm & 5mm wide, all made from polished, hardened steel. 

The handle is equipped with a spring and firing pin, which when turned on opens watch case backs in one micro-choc. The strength of the choc is adjustable by screwing (+ power) or unscrewing (- power) the handle. 

Superb quality, made in Switzerland. Horotec 07.004.