I bought 2 of these one for myself one for my teenage son. He loves his! He slides his keyboard underneath while he's using paper and keeps his pencils sitting on top where they won't get lost. On my desk it lifted my monitor up to just the right height and I've been getting headaches much less often. A plain black plastic letter tray fits perfectly underneath and looks like part of the unit. I should have purchased these sooner.
Wanted it to stack my Cable Box and BluRay player in my bookcase. Have my cable box on top and Bluray balanced "inside" and it works perfectly. Very happy.