These are two plastic farm wire holders. The one on the left is marked U.S.A. It was designed by Woodstream Corporation and sold/distributed by Zareba company which sells farm supplies. You can still purchase this in farm stores. It was patented Nov 28 2013 under US 2013/0313001 A1. It has a square hole in the top that fits a 3/8" wratchet. The second wire holder on the right was made by Dare Co. It is similar in design except it also has a hexshape on the top for a wrench to be used or the 3/8" wratchet hole. Side picture shows the tops. Sorta neat for a modern fence insulator.