Here is a face you may recognize, a true entrepreneur based in Winnipeg, Erna Reimer has been making microwaveable heating pads filled with flaxseed for over 25 years.   Although it is possible to buy heating pads at almost any Drugstore, hers were designed initially for her own use, so they were in effect "road tested" before being marketed.  They are shaped for specific purposes- some for shoulders/upper backs, some for knees, lower backs, eye-compresses, and even a larger blanket that covers the chest and stomach, a favorite is the Tummy Pad for young tummies or older necks.