Very, very thin material. I bought 3 of these and within 5 days one is already in the trash. They came very poorly wrapped. There is a long plastic straw-like piece that is supposed to hold up the cover of the cozy cave. However, they way these beds were packaged, with the plastic supports shoved into bags that were too small and then vacuum sealed shut, destroyed the supports. They were bent so badly they would not conform to required shape. I came home to 1 chewed to pieces on the floor. 
I feel as though I threw $80 in the trash.