A: This hardware is fine for up to 5" square light poles (any diameter round light pole). A light pole greater than 5" square will not allow the banding to get proper tension to hold the hardware against the light pole.
You could use a backer piece, if you feel necessary to protect the pole. Keep in mind, though, the effects of UV deterioration on the rubber. If the hardware and banding are properly installed, a backer should not be necessary,