A friend got me one of these Porter/Delta-Star insulators and the others I got off of an auction site. I always wanted to get these and finally did. These four buss support insulators are made of a polyester fiberglass with a red plastic paint on the outside. The first and third pieces are marked H.K. Porter Company Inc. Delta-Star Electric Div Phila U.S.A.. The ribbed bushing is marked H.K. Porter Company Inc. Delta-Star Electric Div Lybg VA. The first piece in the picture measures 2 5/8" high by 5" width and has a 1/2" threaded insert on both sides, the ribbed piece is 2 5/8" high by 2 7/8" wide and has a 1/2" thread on either side. The cone shaped piece is 2 5/8" high by 2" wide and has a 5/8" thread on either side. The last piece is not marked has a 5/8" thread on either side and is roughly 2 3/4" high by 2 3/4" wide. They are all fairly heavy for there size and tough material. These are still avalible on the auction site but the ribbed bushing they have way over priced in my opinion.