I've installed this 12U rack inset on a 3D-120B stand. It uses the usual diameter aluminium tubing and plastic Jaspers clamps and I easily installed it into my existing stand without disassembling anything.
A generous bag of screws, washers and spring clamps was provided, and installing equipment is quite easy but uses slightly fiddly spring clamps that are pushed sideways into the U-shape rails and then rotated. With practice it's fine but I made sure to install things in order so that if I flipped a clamp round the wrong way I could just slide it out the end of the rail.
It all feels very sturdy and when sitting over on the other side of the stand it doesn't get in the way of my knees. Bear in mind of course that the 12U version means the first tier can't be lower than about 65cm off the ground. Even so, reaching the lower part of the rack requires a lot of leaning or crouching so it's probably best suited to equipment you don't often need to adjust. Nevertheless, I've put a patchbay, a Eurorack case and two semi-modular synths in the rack so I'm going to do a lot of leaning. But I think it's a good, neat and tidy solution for me - now I've got a whole music set-up all on one stand which saves space and means I can (just about) reach everything from one position.
All in all, I'm very happy with it. The Jaspers system is rather expensive but there's no competition when it comes to flexibility and accessories.
