I'm sure this has been covered before, but a search on flexwatt turns up 8975546 billion hits, so I'm just gonna ask a dumb newb question!

Is flexwatt something that has to be ordered? I've done searches on Home Depot and Lowe's sites, no results. I know Petsmart doesn't carry it as I'm there every other day (it seems). I would like to just be able to go pick it up, as my sparkly new plastic tub is having issues. Cool side is ok, but warm side is too cool.