I have them in some of the Blinds I use. My dad swears by them in the blinds he uses now that he is getting up there in age. We typically use an old propane heater that is relatively small and attach it to a propane tank right outside the blind. Then, opening morning we turn the porpane tank on and if it gets cold at all during the season we just turn the valve on the heater onand light it up. It helps on those cold mornings when you want to stay out an extra hour or two. If you have a box blind, I suggest getting one, it really helps when the temps hit 10 -20 degrees.