LENOX Tools Bi-Metal Speed Slot Hole Saw with T3 Technology, Electrician's Kit, 10 Piece 2X more durable with 50% longer life than previous LENOX hole saws Includes the most commonly used hole saw sizes Increased wall thickness improves durability and minimizes tooth loss Optimized tooth design penetrates metal with ease Larger, sharper teeth for faster cutting and SPEED SLOT staircase design for easy plug ejection