So you would like to let your cats out but don’t want them to wander off? The Oscillot Cat Containment System can help. It prevents your cat from climbing over your fence. It blends in unobtrusively with 4-bladed aluminum paddles mounted along fence lines.
When your cats try to jump, their paws go on the paddle which spins, so they don’t get any traction. Pretty clever, don’t you think? More info is available here.