I bought this harness for my 10 pound, very small mini schnauzer.  She is very cute, but not friendly to strangers, and I wanted a way of warning people not to not just reach down and pet her.  This harness seems to do the trick, even if they do think it is a joke.  It fits her very comfortably, and doesn't rub anywhere, and sometimes she just wears it around.  I keep it somewhat loose because of her longer fur on the bottom, but she hasn't managed to slip it, and believe me when she sees a rabbit she tries.