These TeleTone Heel Taps from Capezio are made from Aluminium and are provided with a fibreboard, tacks and screws.
Product Sizing Guide for Capezio Taps
Tele Tone & Duo Tone
Measure the LENGTH of the tap along the bottom of the tap, where it is the widest, and the HEIGHT down the middle, from the very top to the bottom of the tap.
NOTE: that the measurements are that of the entire tap, not the distance between screws.