Thicker, stronger aluminum in an innovative shape that provides increased stud rigidity while reducing track wear Single backer measures 1.250" wide x .145" thick aluminum Double backer measures 1.280" wide x 2.250" thick aluminum (1" hole distance) Radial lobe shape means the weakest flat corner areas of standard backers are reduced so the corners do not bend like standard backers, plus unnecessary weight is reduced Combine the best benefits of square and round backers in one design Available in plain aluminum finish