Insulators are probably the best wood post insulators sold.
These insulators have a large spark flange around the base, and the wire is held further away from the post compared to other H-T insulators. The wire is held in a slot by a removable pin with plenty of space for wire movement to keep line friction to a minimum. The wire can be removed from the insulator while it is still under high tension. This allows the wire to be easily dropped from about 4 posts to drive over it occasionally. The insulators have two holes for either nails, wood screws or staples to make a strong attachment to the post.