St Dormeir’s wool mattress protectors are natural, breathable, and insulating. A mattress should be kept fresh and new with a removable, washable mattress protector. A good mattress will last 10 to 20 years, so you should choose a protector wisely. This machine washable wool mattress protector will not only protect your mattress more effectively than any polyester, but will also actually improve the quality of your sleep as it is breathable and will keep you cool and dry.