Well worth it!!!
I bought the fitted sheet in conjunction with the Term-a-Rest Tech Blanket, and I have to admit, it works pretty well. The sheet has a series of connectors around the edge that hooks up to the tech blanket to make an impromptu sleeping bag (my primary warm weather setup). connecting the the fitted sheet is 3 expanding straps on the bottom with material that helps make it non-slip. I have only used it twice so far, but it has worked pretty well. my biggest gripe is that it is a bit of a chore pulling the sheet over the mattress, but you can live with the inconvenience :) A very well constructed product as well, with reinforcement around the area where the inflation knob is located on a mattress. I believe anyone getting a tech blanket should also get this product as well.