I got this wrench 8-9 days ago.  In that time I have serviced a BUNCH of my watches.  Four battery replacements and 5-6 hazy crystals that needed cleaning.  My largest watch being an Invicta Corduba (U-boat homage) with a 49mm diameter caseback plate, my Russian diver has a slightly smaller case-back and I was able to open that one too without a hitch.  I give this tool 5 stars because it works fine with all my larger watches.  Its probably not as "refined" as some of the swiss made ($$$$) tools, but who cares really.  At $30 it pays for itself in 2 battery replacements.

I didn't have any problems with the included tips.  I used the round circular ones and the rectangle-flat ones.

I would definitely buy this tool again if lost or damaged.