Designed to handle temperatures of up to 150 Degrees C, this twist-on screw set has a fully insulated barrel-shaped phenolic cap, finely ribbed for an easy grip. The black cap has a threaded entry with a wide throat to accommodate 22- to 14-gauge wires with a copper-coated inner spring mechanism to keep the wires secure. It is approved for connections of up to a maximum of 300 volts. Each box contains 100 pieces.