2 of my 3 cats are quite regularly on top of the refrigerator. One likes to nap up there, and the other likes to experiment with gravity by knocking magnets off

2 of my 3 cats are quite regularly on top of the refrigerator. One likes to nap up there, and the other likes to experiment with gravity by knocking magnets off the fridge. The only reason the 3rd doesn't get up there is because she is almost 18 years old and has arthritis and can't jump anymore. When she was younger she would use the fridge as a stepping stone to get on top of the kitchen cabinets and regularly nap there. There is no such thing as a cat-proof vertical height.