Wera Kraftform Kompakt 400 RA SHK Tool Set 1. T-handle screwdriver: The ideal handle shape to allow high torque transmission in difficult tightening and loosening situations. The ergonomic shape of the handle fills the palm of the hand well the fingers lie safely in the soft rounded handle recesses. The whole hand makes contact with the handle and friction losses between the hand and the handle are avoided. Special surface treatment of the blades for high corrosion protection and an optimum fit in the screw head.