PowerPro engineered performance screws for exterior applications. Bronze polymer coating. Approximately 1000 hours salt spray resistance. Made of hardened 1022 grade steel. Star drive provides twice the drive torque of Phillips or square drive. Driver bit in every package. No split twist shank. This design feature creates a hole slightly larger than the unthreaded shank so the shank of the screw cleanly pulls through the top board fastening tight and reducing the chance of wood splitting. No pre-drill bore-fast thread. Patented serrated thread design provides super-fast, immediate penetration into wood, driving the fastener with exceptional speed and force. The lead thread begins a the very tip of the screw which allows the thread to start immediately with limited drill revolutions. Compliant for treated lumber. Bulk.