Calf Taxi is a new invention that is a portable calf warmer, invinted by Marvin L Packard of Springfield, Colorado. Marvin is a farmer and rancher that came up with the idea for a baby calf warmer because he saw the heat from his vehicle's exhaust going to waste. He wanted to put that heat to use. The calf warmer we have goes in the receiver hitch of your pickup. We also have an adapter that fits on the box with a quick hitch that hooks up to your 4-wheeler or side-by-side.