DeWalt EXTREME IMPACT PZ2 Bits, 50 mm, 5 Pieces, DT7391T-QZ

DeWalt EXTREME IMPACT PZ2 Bits, 50 mm, 5 Pieces, DT7391T-QZ

DeWalt DT7391T-QZ is a pack of 5 impact bits in PZ2, 50 mm long. The bits have an extended torsion zone and are made for impact drivers.

The PZ2 recess

PZ2 is the most-used Pozidriv size in Europe. Pozidriv looks like a cross head but carries four extra smaller ribs between the main arms. They increase contact area and stop the bit camming out of the screw - the difference from Phillips, where constant end pressure on the machine is mandatory.

That is why PZ2 is the standard on timber screws, plasterboard, furniture fittings and very nearly everything in installation work in Europe.

The torsion zone

An impact driver delivers torque in pulses, hundreds of times a minute. Without a torsion zone every pulse goes straight into the tip and eventually snaps it. An extended torsion zone is a narrowed section of the shank that twists elastically and absorbs the blow before it reaches the tip.

The 50 mm length

50 mm is the middle length. It gives more clearance than a short 25 mm bit - the driver nose does not foul the workpiece - and stays more stable than the long 90 and 150 mm bits, where any tilt of the machine is multiplied.

Why five pieces

A bit is a consumable. Under heavy use PZ2 wears out fastest because it is used most - and that is exactly when having no spare stops the work. Five pieces means a box that does not run out halfway through the job.

Impact driver or drill driver

These bits are designed for an impact driver but work in a drill driver too. The reverse does not hold: an ordinary bit in an impact driver snaps at the shoulder within the first few screws, because it has no torsion zone to absorb the blows. If both kinds are mixed in a case, the impact ones are the ones with the thinner waist.

Technical specifications

Questions and Answers