We bought this after reading reviews that said it's waterproof. Nope. We have a bedwetting child, and this is after 3 months of using a truly waterproof absorbent mat (that slips around on the mattress, so the urine leaks off it). Water resistant, maybe. I dumped water on it right out of the box, and the water didn't soak in. However, I didn't lie in the water for hours. Clearly, if you have a heavy volume wetter, this isn't the solution. I was quite frankly horrified when I zipped the cover off today. Not thrilled that I discovered this 2 weeks after the return/refund deadline from Amazon had passed.One plus- it really is comfortable. If you need an extra mattress to stash in a closet and pull out for a child's friend to sleep on, this is fine.Also, it doesn't say that it's a twin XL size, just measurements, but Twin XL sheets fit it. This top mattress should go on top of the other inner-spring mattress....then it is FABULOUS! It is slick but that makes it easy to clean, if needed. I wrapped the Gorilla Grip Mattress Gripper XL and that will keep your sheet corners in place at the bottom and top. Also get the ParellBed Sheet Straps Set of 2 Suspender Clips for the top and bottom (one set) and you are Golden. You will sleep on a cloud! The mattress will move a little when you get in and out of the bed, but that is small effort to make right. Drive Medical is usually NOT a fast shipper, first time the Texas Hurricane had hit and the second time who knows but it took an extra week. So don't expect them to keep up with the two day delivery promise of PRIME, so just expect that and deal...ugh...it is what it is. I purchased this mattress for my mother who is confined to the bed, the hospital mattress that came with her bed was just not comfortable, we have had two. Searched amazon and found this one, read the reviews and decided to order. i am so glad it is perfect. It came in a box and i thought ok this is not going to work, it was compressed and low and behold i removed plastic and in about 30 minutes the bed was ready. It is lined so you can sponge it off, i put small washable mattress pad on it and bed sheets for extra protection as i would any mattress for love ones confined to bed, no worries about water soaking or pooling and it is perfect.My mother says it feels great, she did have back aches before in her old mattress, but after several nights on new mattress she says her back feels much better. I took a test on it and i was comfortable too. Thank you Drive Medical Purchased this item for my disabled Father in Law. He says the mattress is comfortable, but could not use it at first. The cover that comes on this mattress that has a handle for moving the mattress around is too slick. He (a 200 lb man) slid out bed. Afterword, he was extremely disappointed and sore and could not use the mattress. This was even with sheets. We removed the cover and the mattress has worked just fine. He sleeps good on it, and has not complained since. I would suggest saving some money and purchasing this same mattress without the cover. Use the extra money to purchase a waterproof mattress pad since this is NOT waterproof and without the cover will not even be water resistant. There was simply not enough support for me. I am in a hospital bed due to a severe spinal injury. I really think it would be fine for some people. Or used as a mattress topper. My caregiver is having a very hard time packaging it up to return. The package did arrive on time. First thing I would tell people about this mattress is, Don't freak out when it arrives. It's packed super tight and vacuum sealed. I've never seen a product wrapped so tight. Once I took the plastic off, it took about a minute or so for all the air to reach everywhere and the mattress to reach its full size. The mattress was everything I hoped for and the price is great. I bought this mattress to replace the mattress that came with the bed on August. 20, 2013, and have slept on it ever since. It is comfortable and is holding up well. I weigh 252 lbs so it has not had an easy life. After almost two years of use, the bed is still in really good shape. It hasn't began ripping nor smelling. The adult who uses it wears diapers and often soils the bed.The bed is comfortable and light weight. The only con is that it is very thin, but the cushion is still comfortable.Great bed for the price.