Kid's backpack is made of waterproof neoprene,same type of fabric they used to make scuba diving suits.This is a type of synthetic rubber-like material that is lightweight and has good water-resistant properties. This bag is very comfortable to wear especially with this foam-like shoulder straps. It's very easy to clean,just used hot water and mild soap to clean the dirty area with and allowed to air dry. This is a backpack that must be hand washed and air dried every time cleaned. The zipper is actually an "inverted zipper". It is great for dust intrusion so it keeps stuffs clean. This bag would fit from 2-6 years old! It measures 11" long x 9" wide x 3.5" thick. It has a long adjustable shoulder straps which is about 13" long (min. length) to 24" (max. length) long. The back and the side pockets is made of breathable mesh fabric for cool and comfort.U can actually store kid's bottle on the side pocket. Has a good size, and is very roomy, has a little mesh compartment good for keeping the smaller utensils, everything stays nice and dry when it rains, and also keeps its shape no matter what. It can keeps beverage fresh for longer period of time that a regular fabric or metal lunchbox. Definitely a cool and very useful little backpack!