I should of added I got mine from a shopping channel in a deal with a set of left hand drills, can't recall the price of both but even allowing for the addictiveness of those programs I would not allow cash to pass through my part Scots hands lightly.
The drills I've used and I'm pleased with (make sure the drills going the right way) the bits that I've used performed aright for the time I used them, like any bits do use the correct one for the correct screw ( I got one wrong and it chewed up as you would expect )