The wera bit check bc drywall construction bit set is suitable for power tools and electronic drills screw depth can be infinitely adjusted and enables flush alignment of sunken screws the drywall construction bits have a modified drive shaft and the bit holder is made from aluminium with an adjustable depth stop contains 1 x 14in 89641 aluminium universal bit holder 50mm9 x 25mm 8511 rz drywall screwdriver bits ph2 9