For the sake of convenience engineers designed the terminal-block screw, which can be driven with either a slotted or Phillips screwdriver. Although a slotted screwdriver can transfer a lot of torque to a fastener, it can slip off the head — not very desirable if you’re working inside a service panel. On the other hand, a Phillips screwdriver stays on the screw head, but tends to cam out at higher torque. To specifically fit terminal-block screws, Wiha designed these cross-slotted screwdrivers, incorporating the best features of both slotted and Phillips drivers.
They test these insulated screwdrivers individually for insulation integrity and rate them to 1,000V, but Wiha claims they’ve tested them to 10,000V. The soft, cushioned grips fit comfortably in the hand and transmit torque effectively to the CRM-72 chrome-moly tool-steel blades. And Wiha super-hardens and tempers the drivers to make them more durable.