Back in the day, there was a metal bowl attached and filled with burning alcohol, and the whole thing could be placed under a chafing dish to keep the food warm, heat was controlled by opening and closing this item.  I do not have the alcohol bowl. The handle is painted wood. 

It is 7" in over all length, and the metal part is 3.75" in diameter.  It is in working order and does open and close with ease.