The Christmas of 1985, my mother-in-law gave us a 14" x 27" Thermophore. It saw much use ...
The Moisture-Plus Covers are specifically made to absorb atmospheric moisture from the air, and also have a reservoir to add water. The cover is one of the key components that allows the Thermophore to produce moisture without having to add water. The moisture comes from cover when it is heated.
The Plus Covers are meant for dry or arid regions that do not have as much atmospheric moisture. You may add water to the cover by wetting the washcloth, which is included and putting it the protective pocket of our Moisture-Plus Cover. Make sure the cover is allowed to dry out and absorb moisture before re-using. In order to prolong the life of the cover, hand wash in tepid water and mild soap then drip dry.
It is a great idea to have an additional cover in the house for everyone using the heating pad.