I use a Watch Wrench to loosen the Backs off of the Water-Proof Watches and then follow up with this really nifty Ball which helps to eliminate scratching the backs. This works great and saves time without twiddling with the wrench. When I fasten the backs, I start with the Ball, and only use the wrench to firmly and securely fasten the backs to the watches. Thanks Eurotool you're the best!