Here is a great early "tipped" 6 volt automotive light bulb mounted in a terrific device, "The R. F. Jaynes Co. Battery & Auto Electrical Tester." The light bulb has a 2.0 inch diameter tip-exhausted glass globe and a double contact brass bayonet style base. The filament is intact and works great. The beautiful mahogany box has wonderful aging and patina color with bright nickel hardware trim. There is a 20 position rotary switch arm on one side for setting range. There are two binding posts on top with two arc gap points connected to a push button located near the center on top. The end panel has one "grounding" binding post and the automotive light bulb test socket supporting the featured round light bulb. The front panel has a wonderful company logo with an image of Mr. Jaynes himself done in gold on black. The entire outfit with auto light bulb measures 9.0 inches long, 3.5 inches wide and 4.0 inches tall.