Bought 3 of these & they're all lined up along the wall next to Izzi's cat tree so when she has a rush o'blood & runs around, she can now run along the wall ! Early days for that tho' she does run up the tree & into the 1st bed in seconds. May need to put a small cushion in the others as they do sag when she's in them, just as a bit of reinforcement when leaping from one to another, but she loves just lying around in them.
Izzi's 4½kg, used the provided screws & rawl plugs in breeze block on outside wall, was easy & they're secure. No need for fancy fittings unless going into plasterboard & that's not recommended anyway.