For cylinders up to 2 inch diameter diameter.

This lubricator should be attached to the steam chest or fitted to the steam line close to the engine. Opening a needle valve lets steam pass into the lubricator .Steam condenses in the lubricator  and sinks to the bottom. Oil is displaced by the water  and passes into the steam line ,lubricating the engine. .Lubricator may be refilled by closing the needle valve, opening the  drain valve to remove water, and removing the cover plug to refill  with oil. 
 Body is ⅝" diameter, total height is 2⅝"threaded ¼ - 40, made of brass.