Just purchased this on Amazon; it was to replace my other one (another brand) that just wore out.  On the first night I tried it a couple of times according to the directions...wouldn't get warm enough.  Second night I added 30-sec in the microwave and it flamed out with several holes in it.  Good concept, just poorly designed...made of the wrong materials for this application; I did, however, salvage the hand warmer pods.  Nope, won't buy another; Amazon still has my old one so I guess I'll buy that one again...