This dielectric union bolt insulator kit consists of two replacement bolt insulators that can be used with the 1 1/2 IN 3003, 3004, and 3006 series, as well as the 2 IN 3001 series, to insulate each bolt in the flange. One insulator is required for each bolt in a flange. The bolt insulators consists of durable, corrosion resistant polysulfone.