【crown hole saw core drill】The 35 mm diameter wall drill is made of metal with a carbide tip, is stable and durable, can be drilled quickly and has a long service life. 【High quality】High frequency welding technology, the welding ports are very strong with smooth welding mouth inside and outside. 【main function】Opening hole operation of wall and brick structures, such as mud brick walls, mixed brick walls, cement walls, moss walls and red brick walls. < p> 【Ideal for】Widely used for installation of air conditioners, oil vapor extractors and open sewer pipe holes, etc.