Copper Crimp Sleeves: Bullet is designed for easy installation and provide an exceptional connection Closed End Connectors: Made from nylon 6/6 (Polyimide 66) Steel Crimp Sleeves: Economical, brass-plated steel provides an excellent low resistance connection UL 94V-2 self extinguishing, closed end style Ceramics: Made of high quality ceramics Have excellent electrical and heat resistant properties Maximum working temperature of 1,000 °F. For applications above 200 °F Uses include appliances, high powered lighting fixtures, ceiling fans, heaters, plastic extrusion/injection molding barrels and similar high temperature applications