Trim, high quality wool covers from Poland. Manufacturer says One Size fits 13-33 lbs, but this color tends to shrink and I would say this maybe fits up to 20ish pounds. There is some shrinkage and felting of this cover. This is a very trim cover. Prefolds or flats trifolded or trifolded and fanned out at the back to get more coverage work well under this. Fitteds are a bit trickier to fit under them. It is designed to go over a narrower diaper such as a pad-folded flat or prefold. The Puppi brand takes special care to ensure that its products are environmentally friendly, which is why these diapers are made from 100% biodegradable elastics. Very high quality Puppi diaper covers are made of two layers of extremely soft and thin merino wool flannel. Once lanolized, these covers hold moisture effectively. Wool is an extremely versatile fabric for cloth diapering-- it is breathable, temperature regulating (perfect for both cold and hot days), soft, and naturally antibacterial. Lanolin breaks down urine into salts and water, so it does not need to be washed as often as PUL diaper covers. Simply hang to dry between uses. However, a hand-washing and re-lanolizing procedure is necessary on wash day. Instructions are included. - 100% merino wool, exclusive of trim - Wool produced and sewn in Poland - Handmade - Requires lanolin This cover is terrific because it's very trim, soft and cool inside because wool breathes.