All bandanas are made of 100% cotton and are machine washable!
This is a snap on bandana but if you'd like to tie before you snap I'd suggest sizing up. Please also consider the fluff of your pet when choosing a size. If a collar snuggly fits your dog at 17", I would suggest size Medium instead of Small because 17" is as far as the Small will go and you'll want a little wiggle room.
M - up to 21"