Features: Special hole opener for wall air conditioning, can be used directly without adding water, with long-lasting sharpness and the ability to drill 300 holes. Three edge drilling is easy, with low cutting resistance and efficient drilling. The alloy welding is firm and not easy to lose teeth, increasing the welding area and effectively extending the life of the drill bit. Quick chip removal without burning the drill to prevent chip blockage, easy hole opening, accurate hole opening without easy misalignment to prevent chip blockage, easy hole opening. Highly concentrics drilling that is not easily swayed. Waterproof, rust resistant, high-temperature resistant, nitriding treatments process extends the life of the hole opener, and easily penetrates various wall. Specifications: Material:Carbon Steel Diameter:30mm,35mm,40mm,45mm,50mm,55mm,60mm,65mm,70mm Package Includes: 1Piece Concrete Hole Saw note: Please allow 1mm errors due to manual measurement. Due to the differences between different monitors, the picture may not reflect the actual color of the item.