If you have a cat that goes outside, please don't use a collar with any elastic because if they get hung up on something they might turn around while trying to get away. This would tighten the elastic and they could very easily strangle themselves.
When buying a cat collar make sure it will unclip if it's pulled on. This should happen fairly easily with just a little pressure. I like my cat's collar to have an identifying tag with his name and my phone number with the words PLEASE CALL underneath. This way IF anything ever happens at least I'll know!
They make collars that break when a cat pulls on it. I think it is called a breakaway but your vet or pet store would know.Better still keep them in. My indoor cat hated a collar and figured how to get out of any collar. We had the collar on him so if he got out. Finally we gave up.