Quote Originally Posted by Rhodes View Post
Thanks. I forgot to say that it's a folding bottle, the correct term is faling me!
Accordion bottle, most likely.

Most here will recommend against these bottles, because they are almost impossible to clean properly, and because they are HDPE and leak air (which negates the expected advantage of an accordion bottle).

My advice - don't bother cleaning - replace with a PET bottle (empty, cleaned soda/pop bottles work well).