Product Features: [Square Hole Drill Bit Set]: 7-piece set includes 1 or 2-Inch, 1 or 4-Inch, 3 or 4inch, 3 or 8-Inch, 5 or 8-Inch, 5 or 16-Inch, and 9 or 16-Inch bits.1 or 2-Inch(12.7mm), 1 or 4-Inch(6mm), 3 or 4inch(19mm), 3 or 8-Inch(9.5mm) , 5 or 8-Inch(16mm), 5 or 16-Inch(8mm), 9 or 16-Inch(14mm). [Steel Alloy]: Crafted from a durable steel alloy with hardness of 40-50 HRC. [Highly Efficient]: Unique design of the drill bit provides a for creating precise mortises. [ Finish]: Designed to provide a finish that 't splinter or tear the wood. Color: As Shown Material: alloy Package Contents: 7pcs Square Hole Drill Bit Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is 1-3cm.