Bottom (underside) is 100% polypropylene.
Dimensions: 19"L x 19"W x 7"H
Machine wash separately, cold water, gentle cycle. Line dry. Do not bleach. Do not iron.
Made in China
Picked up two of these for my dogs. Not the highest quality, but easily fit in the washer and can be hung to dry. I think for the price, they are pretty decent!