Product review (3 stars): Needs a little custom fitting to work for my unit
The idea is simply.  Plug this in parallel with the line going through the cold control so it heats up the area around the defroster sensor/timer unit.  The pad is designed to fit perfectly on a specific unit so you can cut and poke holes as necessary in the foil to fit your unit.  In the instructions provided, the defrost timer screwed down securely on the pad making contact with the wires.  After taping in place in reinstalling my timer, it was on stand-offs so it does not make contact.  I will have to see if it still heats up area enough to work as intended.  If not, I will have to pull up the tape and put something underneath to fill gap which may be a littler hard due to sculpted shape of plastic housing. thinking a foam of some sort.  Will provide update later.  Worst case, fridge/freezer is relocated to basement if this does not work.  Since I had to cut and modify, cannot be returned but not too expensive of a gamble.