Had a watch wrench that came with a 21 piece tool kit but it wouldn't fit my large-ish Invicta watch.
This watch opener is pretty basic but it works, if you tighten the hooks to the grooves on the watch its fairly hard to slip off (with some down-force) and won't scratch the watch backing. I use this in conjunction with one of those watch opener balls (I loosen this a good deal then finish with the soft watch ball so I make sure not to scratch the case.
I can't remember how large my Invicta watch back is (I'll find out and edit this review) but it's large.

I'd certainly recommend this watch opener to anyone that wants a quality product that's easy to use.