All-In-Ones have a waterproof outer, and absorbent inner; making them really easy to use. They're ideal for use by grandparents, childcare providers or reluctant partners, in fact anyone who is unsure about 'getting all the bits in the right place' In most cases, the waterproof outer can also be used as a wrap in conjunction with an absorbent nappy - giving you excellent flexibility when you're out and about.