a bracket at the back wall & 2 top-front screws secure the unit to the cabinet above. under load, the internal mounts bend/deform the top metal of the unit up and out so you cannot get the unit level. we lowered the back bracket another 1/4 inch, but the top of the unit where the screws connect continued to deform outward 1/4 to 1/2 inch. i hope this isn't a design flaw in all units. we did not wish to return the unit, so we installed supports on the underside of the unit to hold it up and only loosely connected the bolts on top for emergency support. i am frankly stunned to come across this basic and dangerous design flaw.  i didn't want to go through a return-and-replace when the next unit might be similarly defective so i kept it in place.