Product Description 2 layer coating insulation with different colors plus a 3rd one in black to further protect handle edges on spanners from 6 mm to 16 mm. Red: safety. Yellow: danger 3 layer coating insulation with different colors plus a 4th one in black to further protect handle edges on spanners from 17 mm to 32 mm. Red: safety. Orange: danger. Yellow: high danger. Material: Chrome-Vanadium steel. Opening tolerance according to ISO 691 From the Manufacturer BAHCO 1000 volt 9 millimeter offset box end wrench is used for protection against inadvertent shock when working on circuits up to 1000 volts. The over all length is 6 inches. It features the two layer coating insulation with different colors. Red is safety and yellow is danger. There is a three layer coating insulation with different colors plus a forth one in black to further protect handle edges. Red is safety, orange is danger, and yellow is high danger. It is constructed of chrome vanadium steel.