Opened package and gave it a good shake and left for fibres to fill out.  This is very good but it does keep me very warm even under a cotton sheet.  For my requirements I had to double this over to accommodate the very hard mattress I was sleeping on and it did made it more comfortable.  I would agree with another reviewer that it really is just like a duvet!  I do feel, however, that with constant use it would flatten quite easily hence 4*  For my very occasional use when visiting family and friends it does the job but may just generate too much warmth for the summer.