USED These metal and plastic, electrical connection pieces are 1 7/8" long with the largest outer diameter being 5/8". The metal threaded area has a 3/16" outer diameter, the same as the inner diameter of the one-piece which is removable. The grooved longer plastic piece is 5/8" high and the other two plastic pieces are 5/16" high. The terminal ground piece has a 1" outer diameter with a 1/4" inner diameter and is 1/32" thick. The original manufacturer and part number are unknown. These come in a package of three.