A while back I won a line spacer insulator in an auction and took a picture of the ones I have. Most of these were made by Porcelain Insulator Corporation (PINCO) under patent number US2,921,112. Now a days they are replaced by plastic spacers which are lighter. All are marked PINCO (Catalog number) Lima N.Y., Pat. 2,921,112 except for the big one which is marked Slacan 1751. Top are L-3190 in gray, L-3181 brown, L-3190 in skytone, Bottom Slacan 1751 in skytone, L-3190 in brown, L-3236 in skytone. Slacan is a Canadian company that is still in buissness today. They were formed in 1912 at Hamilton, Ontario Canada to supply pole line hardware for the Canadian market. There current address is Slacan Industries Inc. 145 Roy Blvd. Brantford, Ontarion Canada N3R 7K1. They also have this style in brown.