This special 3 in 1 fits both 1.25 and 1.33 lb metal T posts, can 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 or attached with nails/screws to wood or vinyl. The insulator will accept large products up to 3/8 inch (9.5mm) diameter. It is excellent for high tensile steel wire, insulated electric wire and polyropes. It comes 25/bag and is available in black or white. Screws/nails are not included.