The Wiha 28789 11-Piece Insulated TorqueVario-S and Slimline Blade Set, individually tested to 10,000 volts AC, is designed for precise torque accuracy of +/- 6%. It's 33% narrower blade shafts let you reach deep set terminal block fasteners, and its direct molded insulation ensures protection against arc flash explosion. With a designed life of 5,000 cycles or 1 year and individual serial numbers and Certificate of Calibration for warranty claim protection, you can enjoy safety and peace of mind.