It's difficult to review a product that has no equivalent in the market, but in spite of my initial scepticism, I have to say I am impressed; they do give an unusual and interesting sleeping experience. They are light in weight, and give a good degree of 'climate control' - they would be excellent as a sleeping bag liner when camping! I have been using one during the recent hot spell in place of other bedclothes, and they give just the right level of warmth.
Judging by the way they have been selling, lots of others agree with my findings. Well worth a try!
L4M 240 Body Cocoon