We have "Basic WellB Hundeseng Madrass" which our dog likes a lot. As we wanted to get a bed, we bough this one. The center part is taller than the rim (?!) and behaves like a pillow, not like a mattress - dog constantly changes position and doesn't look too comfortable. Loose pillow means also that he is dragging it and prefers to play with it than lay on it.
In the end we gave up trying - the rim part is on top of the "Basic WellB Hundeseng Madrass".
Very strange design - the pillow should at least be attachable and fit to the rim/frame. Big NO from us.