Almost the last word on drivers...

[Juantxo]

In reverse order (from left to right) of best to worst, please find the screwdrivers I have used on Oyster and Jubilee bracelets of 36 to 40mm Rolex watches. The best is no doubt the Rolex 2100, the worst the Bergeon 1.6mm. A close second in bad is the 1.6mm Horotec. The second from the left is a fine screwdriver although the blade is ever slightly thinner than the one on the 2100. Please note that some of the drivers are marked as 1.6mm and others 1.8mm, some are concave, others flat.

I hope this helps.