Product review (5 stars): Great to make a large cooler out of your freezer!
Pricey but worked very well at keeping my chest freezer between 33-38 degrees while hauling caribou meat back from the Yukon.  It was great to have a "large cooler" for the meat and not have to mess with ice and water rather than a bunch of frozen chunks when I got home.  I did have to play around with the settings to get the temps I wanted, the dial isn't too accurate.  Worked much better than the initial cheap POS I tried initially!