Milk stirring paddle for cooling milk.  The paddle is made of galvanized sheet metal, with tinned seams for sealing against it filling with milk.  The tool is hollow and a little over 19.5 inches long.

In the early days of milking cows here in the Dairyland, milk from the cow was placed directly into milk cans that were sitting in cold spring water in the milk house.  This tool would be used to stir the milk to make sure the whole milk can would cool down sufficiently.