Had a GE Profile Spacesaver 1800 and stayed with GE to make sure the fit wouldn't disrupt our expensive backsplash.  It didn't!!  Perfect fit.  The only thing we miss are the quick buttons for 1-6 for minutes.  Getting used to the dial, but like it and the sensor is great for popcorn (last unit would burn every time), heating a beverage, and much better for cooking.  Happy to have made the upgrade.