The Slumberdown Firm Support Back Sleeper Pillow 2 pack cleverly regulates your temperature, so you don’t get too hot or too cold as you sleep. Containing a scientifically proven Dacron hollow fibre fill, this specially developed filling has been formulated to carry excess heat and moisture away from the surface of the pillows – drawing it from your head and body so you keep it at a regular temperature. The more heat you generate, the harder the filling will work to keep you cool. But if you’re already cool, the clever Dacron hollow fibre filling won’t allow you to get too cold either. As well as helping you have a comfortable night, you can also sleep easy knowing that there's nothing in this 2 pack of pillows that could cause allergic reactions, as they're naturally hypoallergenic. Having a firm support level, these pillows are a great choice for side sleepers, or for those who prefer a firmer, more deep pillow.