This is an NOS 6V spotlight bulb which measures 4.4" in diameter and includes the pair of screws on the backside for attaching the wires.  It was used in spotlights from the 1940's, 1950's sold by Ford, Lincoln, Mercury, GM and other vehicle car and truck manufacturers who sold spotlights including those made by Unity.  This bulb was tested and is in working condition. Perfect for replacing a missing or damaged bulb or one which has pitting in the glass or for a spare.   See my other eBay auctions and eBay Store for hundreds of other Ford and Thunderbird parts including the NOS 6V and 12V hand held lights,  spotlights and driving lite bulbs.  We charge actual shipping only and are always glad to combine shipping on several auctions or you would be welcome to pick them up at our shop. Thanks