This is a multi-purpose special 3 in 1 insulator that works on T posts wood posts and some round posts. Great for high tensile steel wire insulated electric wire and will accept polywires and polyropes up to 3/8 (9.5mm) in diameter Fits both 1.25 and 1.33lb metal T posts. Can be nailed or screwed to round or square wood posts as well as vinyl posts. They can also be attached to a steel pipe/post or to any surface that will not accept nails or screws by tying with wire through a mounting hole on the back Screws/nails not included. Packaged 25 per pack Main color is White Brand : Field Guardian UPC : 814421013125 Model NO : 653115