The underquilt was bought for hammocks from the same manufacturer. Tested several times during the summer season, mainly while spending the night in the forest. For me, definitely a "must have" for comfortable hammock sleeping. Previously, with a sleeping mat in the hammock, I couldn't close my eyes because every movement would make the mat slip out from under my back. The underquilt wraps nicely and always stays in place, even if you toss and turn for half the night. I can't imagine sleeping in a hammock without an underquilt anymore. I highly recommend it!