This is a simple but effective shelter for Feral cats or stubborn cats that won't go through a regular cat door. It's made from either a 48 qt Rubbermaid cooler. These coolers are very well insulated and do good at keeping the cat's body heat in, we also include a bag of straw to provide extra insulation to compensate for the unobstructed door opening. The cooler has been turned upside down to make it waterproof, otherwise wind driven rain could get in around the lip of the lid. The round entrance has a PVC liner so there is no exposed insulation. The 2nd opening is a regular Cat door with a flap, we have found that even though some cats wont go thru a flap to get into the house they have no problem going thru a flap to make a quick escape from a house. Beware of Pods that have exposed insulation around the entrance as this an ideal place for dirt, mold and mildew to accumulate and is very hard to clean. Fits one average size cat up to 14lbs.