28588 is a 5/32inch hex TorqueControl blade. It is designed to be used with Wiha TorqueVario, TorqueFix, and iTorque, screwdriver handles only. This is not for use in Wiha in insulated torque handles, esd torque handles, T-handles, or torque wrenches. The torque blade can be inserted into the Wiha torque screwdriver handles to create a solid screwdriver handle with a torque setting. The fixed blade eliminates the potential for play and wobble caused when using a bit or bit adapter. The fixed blade has markings with their size and max torque ratings for easy identification.