The Moist-Sure Covers are specifically made to absorb atmospheric moisture from the air. 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.
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.
Model 164 (4"x17")
Model 162 (14"x14")
Model 161 (14"x27")
Model F01358 (18"x36")
It is great to have an additional cover in the house for everyone using the heating pad.