My ferrets like digging in the thin layer of usually gray or black cloth that is on the underside of the box springs. The easiest way I found to bed proof is to just flip the box springs over and put the mattress back on top. They aren't interested in digging at the thicker cloth on the upside of the box springs. I did this at home and I do it at hotels that I take my fuzzies to. I can't tell the difference in the way the bed feels when lying on it. [Posted in FML issue 3029]