This blade is used in a table saw to make special joinery cuts. A Dado cut is a wide groove made in one piece of wood in order to join another piece. This one wobbles: when sitting in the table saw, rather than spinning true, it is offset and wobbles. As it spins the blade moves back and forth at a very high speed, cutting away the material being passed through. You can set the blade to wobble wide or narrow, controlling the size of the slot you are making.