I was using normal dewalts and going through atleast 2 every couple of hundred screws.Ive tried the dewalt "impact" ones, which are pants and would sometimes break about every 5 screws. Then I had some of these come free in a box of 600 screws. 5 free bits and I can honestly say one bit would easily last through a box full of 80mm screws! They seem to last for ages. And I've probably got about 50 spares now just from them coming free in boxes of screws I've used. If I ever run out, I'll definitely be buying more. http://www.timco.co.uk/power-tool-acces ... mpact-bits