I spent many hours researching orthopedic dog beds when I first saw my 4yr. old hunting dog having a hard time getting up. My heart sank, and I thought it to early for arthritis or hip dsyplasia but that I would get an orthopedic bed anyway.After much reading it looked like the memory foam pads would be better than any foam fill that would sink in the middle.I first bought a memory foam from "dogbed4less" to see if the dogs (2 hunters: 60lbs and 75lbs.) would like it. After seeing they were happy I thought I would get another one from a different company since so many of them sounded good. Next I ordered this one in the gel memory foam from "dogonit" sold by "back support systems". Last I ordered from "K9 Ballistic" and outdoor orthopedic bed.All the beds are excellent and both dogs sleep on all 3. They share the outdoor xlarge bed..All the beds have a waterproof backing or a waterproof inner liner so the memory foam is protected. Both indoor beds I purchased with the microsuede cover. "dogonit" cover is alittle thicker than the one from "dogbed4less" but that maybe because it has the waterproof backing on the suede and not a separate nylon liner as the dogbed4less."All are extra thick 4" to 5" with a firmer foam underneath for support. dogbed4less has a sale on 3" beds but I think the thicker is better for large dogs.I emailed dogbed4less with some questions and they quickly responded.I phoned dogonit with some questions and they answered my questions. (They will be making other sizes.)I did not try and contact K9 Ballistics.I cannot comment on the longevity of the beds as all are new.Look at the picture of the gel memory foam on this site and the top foam acts just like the picture. It is "buttery soft" and springs back slowly just like my tempur-pedic mattress. This is the best mattress.All 3 are nice beds but the gel memory foam by "dogonit" is really top of the line and the grade of foam is superior.