Gisafai 7 Pcs Square Hole Drill Bit With 1 Square Hole Drill Bit Adapter Product Features 7 Sizes Drill Bits with Adapter: includes 7 different sizes of square hole drill bits, namely 1/4 inch, 5/16 inch, 3/8 inch, 1/2 inch, 9/16 inch, 5/8 inch, and 3/4 inch, to meet your varying needs, as well as 1 piece of square hole drill bit adapter; Use different sizes of square hole drill bits, matched with the appropriate power of the square hole drilling machine, you can drill square holes to meet your requirements Square Hole Drill Bits: crafted from quality bearing steel, these mortise chisel drill bits boast an extended core, incisive cutting edges, and continuous blade; Such construction ensures rapid cutting and a firm fixation on the wood; The set is only for open square holes and locking drills, square hole drill bits cannot be applied on electric drills and bench drills; It requires the installation of a square hole drill (mortising machine) to drill square holes Square Hole Drill Bit Adapter: this square drill bit adapter is constructed from all steel casting, ensuring durability and longevity; With its length of approx. 6.3 inches, 0.75 inch top inner diameter, and 2.17 inch bottom diameter, the adapter reduces the usage error, providing a more precise drilling performance Efficient Combination: the adapter is compatible with all the different sized mortise drill bits for wood, whether you are a beginner or an expert, each drill bit is designed to drill precise holes with minimal pressure, significantly reducing the stress on the operator and enhancing work efficiency, bringing much convenience in construction, installation, and decoration industries Widely Applied: these square mortise drill bits with adapter are ideal for both DIY enthusiasts and skillful workers, suiting well for construction as well as woodworking; They are suitable for variety of lower hardness materials, including compressed board, plastic, density board, sandalwood, pinewood, and so on; This makes it applicable for various sectors including DIY woodworking, construction, and decoration Shipping: Shipping is complimentary within the lower 48 US States. We Do Not Ship to PO/APO Boxes, HI or Alaska We Do Not Ship Outside of the Continental US All items ship within 24-72 hours of Payment For large items that require Freight shipping a valid phone number is required to call and schedule your delivery Terms of Sale and Feedback: Feedback is extremely important to us and If you are satisfied with our transaction, please take a moment to leave Positive Feedback. YOUR Satisfaction is our #1 Priority! If there are any issues, PLEASE contact us BEFORE leaving a neutral or negative rating so that we may resolve any concerns. We PROMISE we can make you happy if you give us a fair chance. Returns / Concerns: All items qualify for returns within 14 - 30 days of receipt. Buyer is responsible for return shipping on any item that is not damaged Please be sure this is an item you want before making your purchase. Customer Satisfaction is our TOP priority! All items are IN STOCK at time of listing. Inventory changes constantly and it is impossible to maintain a perfectly accurate count of all items. Please do not penalize us if we have to issue you a refund! Thank You For Your Business!