1. Material ; brass and rubber 2.Durable,safety 3.Good price 1.connector covers are molded form a special heat and cold resistant material 2.covers have no metal liner to rust or corrode.3.Neoprene rubber cover,good insulation and conductivity.4.Brass parts material: Brass C37700, CW612N, are CNC machining YJ98-12 japanese type cable terminal