The Strong-Grip seat firmly secures I-joists with flange thickness from 1 1/8 in. to 1 1/2 in.No joist nailing required for standard I-joist installation without web stiffeners.Actual Joist Size: 1-3/4 in. x 9-1/2 in.Made from 18 gauge steel.Galvanized for extra corrosion resistance.