Here are two unique lag screw wire holders. The first one on the left is sold by Line Material Company before they had the LM in a triangle. This piece has the catalog number on the front and below it an upside down L in a triangle. On the back is Patent Pend. and a Colonial Insulator Co. marking who made it for them. The one beside it is a common Knox K410 only the Knox is upside down. The back is correct. OOPPSS.