I bought a Steel Box 2 and a Steel Box 6 with 3 pieces Thon Rack Trays 1U, which fit them perfectly. Some of the posts here about Steel Boxes have complained that they are not very stable and sturdy, and that the back edges cut the hands. Clearly one of these are false posts. I think it's absolutely rock solid, could withstand a nuclear attack, I've installed my RME UFX II and a few other expensive gadgets in it with complete confidence. The shelves are brilliant too, finally there is a lot of space for cables. The recommended screws have to be bought separately along with the rack nuts, but in return everything fits perfectly.