After getting the unit together using the pre drilled holes & screws the unit completely collapsed with each of the pieces lying separately on the floor. The factory machined flanges (which were pre-inserted into the holes to secure the included machine screws) were not the exact depth and the screws went through and beyond the flange forcing the shelves away from the sides. When I placed the finished assembled unit upright it completely fell apart. I had to get longer wood screws and re-drill all the holes and replace the machined screws with new wood screws. Very disappointing. Not HAPPY!