TOPSHEET: Co-extruded nylon. BASE: The Crown 4000 base material holds wax at any temperature. EDGES: Special SAE 1070 T Rail with a 48RHC hardness. SIDEWALLS: Anti crush 9.5mm UHMW sidewall. CONSTRUCTION: Triaxial fiberglass over a laminated poplar wood core. A layer of unidirectional 9 ounce fiberglass is also laid on top for torsional rigidity and flex. Rubber dampening.