Purchased this for the KM18813 arms that I bought as part of the KM18810 set. After setting up the stand and arms I set an Access Virus desktop sound module on top of the arms but given that the module is kind of small, it wasn't ideal. The KM18813 arms themselves weren't level and it was an awkward setup at best.
Getting the tray was well worth it. It's fairly sizable, allowing me to fit the above Virus module and a Kaossilator 3 Pro alongside it with plenty of room behind to spare. In the future I will likely swap out both units for another synthesizer or look to mix 'n' match different modules.
The KM18819 tray is made of steel and features a lip at the bottom end. Said lip contains a rubber fiber along it to prevent any modules from getting scratched or from damaging the lip itself. The back of the tray angles around the KM18813 arms to keep it firmly in place and there is a hole that makes it easy to handle wire management and for carrying the tray around if you intend on moving it frequently.
All in all, this is the perfect buy if you're looking to put smaller modules on top of the KM18813 arms. Plenty of room to work with and you could easily use it on top of desks or the likes if you just want a slightly angled workspace for your modules.
Pros: Durable, covered lip to prevent items from sliding off without damaging them, hole for easy carrying or for filtering wires through, plenty of space.
Cons: Could be a little longer, additional hole or two on each end would be useful for cable management.
Very happy with this purchase. Perfect for what I needed and would highly recommend if you're looking to use multiple modules together on top of the KM18813/KM18810.