C k blue steel impact screwdriver bit pz set of 10 t4510 manufactured from specially formulated v8 steel alloy for extreme toughness features torsion control technology to withstand the stresses of high torque applications blue steel impact bits provide a vastly extended working life colour coded for convenience set contained in a convenient bit storageplete with bit holder bit sizes pz1 x2 pz2 x 5 pz3 x1 ph2 x1