Alumina is constructed from a single sheet of aircraft-grade aluminum. The molecular rebonding from the machining process creates a highly rigid structure for maximum durability. It is then sand-blasted for a texture that further aids tracking precision.Alumina is constructed from a single sheet of aircraft-grade aluminum. The molecular rebonding from the machining process creates a highly rigid structure for maximum durability. It is then sand-blasted for a texture that further aids tracking precision.