"I just got my first ferret, who is about 5 months old, and she is very hyper and playful. I have three cats and all are outdoor, and so I have a a doggy door for them and my dog. Also, my house is pretty big and old, and their are lots of cracks and places to hide for a ferret. Because of all these reasons, I purchased this harness, so I could take my ferret around the house and not be worried about her running away.
It's slightly too big, but I just make it tighter with a safety pin and it's all set.
Even when it's tight, she will eventually wriggle out of it, and so I still close all doors to the room I'm in. I wouldn't risk going outside until she's older and I can almost guarentee that is will be a bit tighter and snugger on her.
Although with these cons, I didn't really expect any better, especially with a ferret, so I recommend it!"