Thon 4U Live Rack rail

Bought this set to add rack units to the back of a Flyht Pro Rack 4U. Fits in perfectly (I did not need the wood blocks). Be aware, though, that the rails do not have a notch on their side to slide M6 nuts. This means if you set up the rails, lock them with the rivets, but you forgot to slide all the necessary nuts for your units beforehand, it's game over and you have to disassemble the thing. I'd recommend locking the rails using bolts instead of rivets.

I've used it to make a custom rack for my project studio. Only bad thing about it are the rivets, in my set about 2 or 3 where faulty. Overall, nice product.