Here is a link describing these screwdrivers: http://www.leevalley.com/wood/page.a...,32219&p=32219
I bought two complete sets about a year ago, one for me and one for my daughter Kristel. I really like using them both because the grip feels better than any other screwdrivers I have used and because the tips fit well into the screw recesses.
But, I have already broken three tips (one Robertson #0 and two Robertson #2). In each case the metal within the tips sheared, causing a part of the tip to break off and leaving the other part of the tip still in the driver. Since there is a Lee Valley store about a 15 minute car ride away and since I visit it often, it is easy for me to pick up replacements. But, most folks on this forum are not so fortunate.
It is possible that only the screwdrivers with the Robertson tips are prone to this breakage (but 98% of the screws that I drive are of the Robertson variety).