Hi ZhivagosGirl,
Mattress protectors (usually covers refers to the cover or ticking of a mattress) involve a series of tradeoffs between breathability and temperature regulation, how much they affect the feel of a mattress or the foam below it, and the degree of waterproofness that is suitable for a particular person or use.
There are quite a few threads and posts in the forum that contain lots more information and a forum “title search” on either “protect” or “cover” will bring up enough of them to get a clear idea of the tradeoffs involved in your choices. A general search on “protector” will bring up even more that you can scan through but post #89 here is probably the best source of information and talks about the tradeoffs between different types of mattress protectors and links to some good sources for each of them.
Dormeir, Natura, and protectabed are all good products for those who want the specific properties and qualities of each of them. Dormeir is probably the best of the thinner stretchy wool protectors and they are well worth the price for those who are looking for the specific qualities of a wool protector which is water resistance, temperature regulation, and who don’t mind a little bigger effect on the surface feel of the mattress. Protectabed is one of the thinner “membrane” types that are waterproof, have little affect on the feel of the mattress for most people, but can increase the heat because they are less breathable than wool or stretch cotton.
Phoenix