The vertical scale works by a dog running up the wall, the dog has to grab and hold the toy, we use any toy you like, as long as the dog actually grabs and holds then thats a pass at that height, we move the toy up a foot or 1/2 a foot and do it all over again until the dog does not reach the toy, the dog is given another chance at that height, if they get it then we carry on until it fails twice in a row! We always give the dog one last play after it has failed It is a good day out and the dogs love it!