Square Hole Drill Bit Set: Includes 1 square hole bit adapter and 4 square hole drill bits. Compatible with bench drills and hand drills featuring chuck diameters from 38 to 55 mm (1.5 to 2.2 inches). Designed for easy installation and use. Intended only for bench drills and hand drills with chucks.Quality Materials: The square hole drill bit adapter is made of high-quality steel, offering strength and durability. It securely holds wood during drilling and accommodates various mortise accessories. Precision-machined cutting edges minimize operational error. The design prevents clogging by wood chips. Features high hardness, resists slipping, and enables efficient cutting.Efficient and Accurate: The adapter and four included drill bits provide versatility across common sizes. Precision engineering ensures accurate mortise hole drilling. Offers a convenient and faster alternative to traditional mortising machines.Widely Applicable: Helps reduce physical effort and improves work efficiency. Suitable for construction, carpentry, DIY projects, and interior decoration. Works well with low-hardness materials including particleboard, plastic, MDF, sandalwood, pine, ash, and similar woods.Dual Support Bracket: Square hole drill bits are reliable and practical for use with bench drills and hand drills. Ideal for woodworking, furniture manufacturing, and related applications.Note: Slight color variations may occur due to lighting conditions and screen settings. These differences do not affect functionality.Material: Steel Color: As shown Package Contents: 1 x square hole bit adapter 4 x square hole drill bits Note: This package includes only the items listed above. Other accessories or tools are not included. Measurement tolerance: ±1–3 cm.