Our Rigid Blue Backer Pad is a light weight, ultra rigid, mounting option. Each backer pad has a Velcro face, to mount one of our polishing pad options, and a 5/8"-11 Threaded Adapter, to fit onto any grinder. The Rigid Blue Backer Pad is available with and without a foam buffer option. The added foam option is an extra feature for those who are looking for the lightest amount of play while polishing.