The Wera Kraftform 160 i/7 Rack Screwdriver Set Kraftform Plus Series 100 includes voltage tester and rack 7 pieces. Our screwdrivers are tested for dielectric strength under a 10 000 volt load to make sure that their most important property their insulation has been exhaustively tested. Each individual Wera VDE screwdriver is subjected to this test to guarantee safe working up to 1 000 volts. A precisely-focused laser creates a sharp-edged surface structure. This laser treatment results in an edge hardness of up to 1000 HV 0.3. Wera Lasertip "bites" itself into the screw head and prevents any slips out of the recess. A precisely-focused laser creates a sharp-edged surface structure. This laser treatment results in an edge hardness of up to 1000 HV 0.3. Wera Lasertip "bites" itself into the screw head and prevents any slips out of the recess.