Purchase Notes:The square hole drill bits need to be used in conjunction with the mortise machine.Please make sure that the wood borad and the drill are at a 90 degree angle. These drill bits not usable with a hand held drill. Easy to Drill:The carbide drill bit tipped is and wear-. With high hardness and long service life. The drill sleeve has a U-shaped design to facilitate the discharge of wood chips and improve the drilling efficiency. Widely Applications:This square hole drill bit is suitable for wood, including MDF, MDF, particle board, channel wood, pine wood, basswood, etc. Note: It is not suitable for processing metal, glass, plastic, concrete, gypsum board etc. Colour:As Shown Material:45 Carbon Steel Package Contents: 6 * 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.