The MB- and MC-models are delivered ready for installation as separate units. The cabinet size are the same for both models but the covers protecting the access into the grinding unit are different.
The lid on the MB model completely covers the inlet into the grinder. Food waste is fed into the assembly before the lid is closed and the grinding process begins. The MC model has a lid which only partly covers the disposer inlet. This permits food waste to be fed into the disposer but prevents access to the grinder.