My runs are all chain link dog pens with chain link across the tops. We built support for the chain link on top using posts or top rails cut to size and connected with standard chain link hardware and connectors we bought at the local DIY store. Each run encloses a coop that the birds go into every night that is closed up tight, so in the event something did get in, which (knock wood) so far hasn't happened in 10 years, they couldn't get to the birds. If I had mink/weasels in the area the runs would would definitely have to be lined with hardware cloth, or surrounded with electric fence or electric net. We do have fox and coyote and many birds of prey, and of course the occasional neighborhood dog, which is the only predator I've ever lost a chicken to. If the runs are 6 feet tall, unless you are tall, you will be able to walk in after the cover is on and not have to crouch. Best of luck to you.