●This screw nail drill adapter is a accessory for dowel maker,use it attach square blanks to your drill. ●Find the center of the square stock first, use a 4mm drill bit to pre-drill the hole,clamps the adapter in the drill and drill it into the pre-made hole, then you can start making dowels. ●It can attach square stock to the drill without being limited by the size of the square stock. no longer have to do more freehand whittling or search for corresponding sockets for different sizes of wood.It makes thing easier. ●Made of stainless steel, coarse thread, dimensions 16*16*42mm, come with a 4mm drill bit. ●10mm hex shank, requires your drill be able to hold a 10mm drill bit.