Fits Bosch models UM3 and any of the MUM6*** series. This blender has stainless steel blades that are scientifically bent and twisted to rotate food. When running you will see that blended ingredients move up the sides and then pulled down the center. The blades are removable via a wrench built into the blender lid. Coupled with the 700 Watt motor in the "6 series" Bosch mixers, this is a most amazing blender.