Wera Tools - 840/4 IMP DC Hex-Plus DIY Impaktor bitsHigh quality Impaktor bits for hexagonal socket screws. The Impaktor technology offers an above average service life even under extreme circumstances. Enhanced friction resistance, thanks to the rough diamond particle coating on the bit tip, prevents any slipping out of the screw head. Hex Plus ensures a greater contact surface in the head of the screw. The notching effect is therefore reduced to a minimum and damage to the screw head more or less