Item # ELF-RS-25,  Elfin Electric Fence Insulator.  NEW Desigin A proven insulator, this new Elfin has only one wire holder.  The insulator accepts any standard fence wire or polywire. Should not be used for Polytape or Polyropes. Weather resistant black polyethlene performs in any climate, Black only, Nails not included. Use double headed nails or screws to fasten to wood post. Packaged 25/bag.