.064" think spun aluminum cylinder. Vented for proper ballast operating temperature. Polyester powdercoat exterior finish with factory standard finishes White (WHT), Black (BLK), Bronze (BZ), Silver (CS) (Standard), Custom Color (CC). UL Listed medium base porcelain socket, with nickel plated brass screw shell. Incandescent BR40, PAR38, A23, A21, Medium Base. (300W PS35 Mogul Base Consult Factory.)