Answer Grant, The nut holder WB01X10071 is part of the outer cabinet, and the purpose is to mount the microwave to the top opening in the cabinet, through the bottom of the cabinet shelf/frame. You'll need top purchase three(3) "machine" screws, measuring 1/4 in shaft, 28 in thread and 3 1/4 in. long. We're also sending you some installation information, which should be helpful. Read More... Answered by AppliancePartsPros.com | Wednesday, July 11, 2012