NSi easy-twist twist-on wire connector. Flame retardant UL 94V-2 thermoplastic shell provides excellent electrical insulation. Temperature rating 105 Degrees C (221 Degrees F). fixed, precise square wire spring provides secure gripping of conductors. Deep skirt entry provides protection from flashover and shorts. Sure-Grip ribs improve gripping ability and comfort. Compact design ensures proper installation-especially in tight spaces. Threaded Tunnel entry guides the wires into the connector easily. Pre-twisting of wires is not necessary. 1,000 Volt maximum in fixtures and signs. For copper wire only.