Only 1 drill piece was used for iob and then not needed again. The Site Tuff Dry Diamond Core Set is a 12-piece drill bit set designed for use with drills. The set includes a variety of bits suitable for different drilling tasks, with one piece being a bit that has been used. The high-quality brand, Site Tuff, ensures durability and reliability for your DIY projects and workshop needs. Each bit is securely stored in a case for easy organisation and transportation, making it a practical addition to any toolbox.