If you have an 8u Thon rack, then these rails will already be installed on the front side. I bought this set, because I wanted to mount a heavy/deep power amp and it's recommended to fix these on the front and back.
Installation is quite simple. The rails are fixed to the wooden/laminate blocks and the blocks are held in place with pop-rivets. The reason that there are 4 blocks and 2 rails is that the blocks fit around the butterfly clasps left and right.
I managed to install everything in under 30 minutes, but to get the job done you will need a drill and a pop-rivet gun. Some kind of clamp to hold the blocks in place when you drill would be handy.
Once in place, the rails themselves are excellent. The nuts can be positioned wherever you need them to fit any 19-inch component, no matter what the spacing of the mounting holes.
Thoroughly recommended!
