So my cat is an expert at removing her collar. I'm lucky if one will last a week usually a day or two. We live near a main road and I like her to have a collar just in case. Got her a Beastie Band and she's had it for six weeks and is still going strong. It's a soft stretchy material and has a Velcro fastener. Just thought I would post in case it is of use to anyone. I got mine from E Bay.
www.thecatconnection.com/cats/everyday-beastie-bands.html