You are bidding on a Big # Radio Corp watch case battery test volt ammeter made in the late 1920s. It is in nice original condition with bright nickel plating.   is nice on top, but there is corrosion on the bottom.  It reads up to 50 volts, or amps.  It is designed for testing of  batteries used with early battery sets from the 1920s. The original lead which plugs into the top is present.  It measures 2 inches in diameter, and 3/4 inches thick, not counting the lead or contacts.  I have not encountered this brand before.  It is a nice accessory item for your collection.  Shipping weight is 8 ounces.  Please see my other auctions for more interesting radio and audio items, and tubes.