The industry standard twist-on connector with top quality, performance and durability. Tight, square-wire spring makes quick, secure connections for positive continuity. Tough, thermoplastic shell shields against environmental extremes. Resists chemical action from hydrocarbons, diluted acid or alkaline solutions. Flame-retardant properties resist heat distortion up to 105 C (221 F). High-dielectric shell features deep skirt design to prevent exposure of bare wire. Copper-to-copper connections only.