Please Note for Your Safety: the power tool adapter is screwed into the circle saw bit in a clockwise direction. Therefore, when making holes, please drill in a clockwise direction to avoid the connecting rod of the hole saw from unlocking and falling off due to counterclockwise rotation Round Hole Cutter with Clockwise Forward Gear: this wood hole cutter has a clockwise forward gear mechanism that prevents binding in plaster boards and plywood. The bi metal construction handles up to 6.1 inch holes for recessed lighting. Includes a hole saw mandrel for quick swapping Carbide Teeth Hole Saw for Accurate Diameter Cuts: this carbide teeth hole saw holds diameter errors under one millimeter when cutting through soft metal and pvc. Optimized tooth geometry delivers faster plunge cuts. A reliable hole saw arbor connection keeps the bit stable on standard drills Bi Metal Hole Saw for Wood and Soft Metal: this bi metal hole saw cuts smoothly through wood boards, gypsum boards, and soft metal sheets. Its high speed steel teeth reduce heat buildup so drywall hole saw tasks finish faster. The spring loaded pilot bit centers every cut accurately Hole Saw with Spring Loaded Pilot Bit: this hole saw uses a spring loaded pilot bit that ejects cut material automatically after drilling through fiberboard or pilaster boards. No prying out plugs saves time. Ideal for metal hole saw applications on thin steel sheets