Extremely durable bi-metal blade that does not wear out with rough use. Suitable for drilling wood with nails and is 50 times more durable than standard blades intended for wood with nails. FOR WOOD AND WOOD WITH NAILS SIDE BLADES - More accurate hole with less tearing THREADED TIP - Faster drilling with less force required TAPER THREAD - Reduces friction. Tri-Flute construction removes chips effectively FULLY HARDENED - Increases durability 1/4" INCH QUICK CHANGE NECK - Fast and secure clamping