When I receive them frozen, I place each rat in an individual ziplock baggie. The night before feeding, I place bagged rat in refrigerator. When my BP looks active and ready to eat, I take the rat from the refrigerator and place into my "cooker". This is a large, deep plastic container filled with very hot water with a gallon size ziplock draped over the container's edges, making a dry, warm "waterbed". I place the bagged rat down inside, weight it down with large, polished rocks, then put the lid on , catching the edges of the gallon ziplock. I check about every twenty minutes until the rat's completely warmed and ready to feed. Kinda hard to explain, but it's really easy!