The Rumparooz Onesize Cloth Diaper has 4 sizes which are adjustable by the rise snaps on the front of the diaper. The Rumparoozis the first onesize diaper that starts fitting at 6 lbs, no more waiting for your newborn to put on a few pounds before wearing cloth diapers! Available in both Snap and Aplix (Velcro) closure, the Rumparooz are a pocket diaper system. Each diaper comes with a "6-r soaker" which has 6 absorbency and size setting to best customize the fit and function of the Rumparooz for your child. The 6-r soaker is inserted in the pocket opening on the inside of the Rumparooz to make the diaper absorbent. The Rumparooz diaper itself is made of a PUL (1000 thread count polyester interlock knit with a urethane laminate) which is waterproof. The inside of the diaper, which lies against baby's skin, is a scrumptiously soft microchamois which is 100% hypo-allergenic and no-pill.