This offer is for what I'm guessing to be a WW2-vintage Aircraft Engine Hour Meter, made by John W. Hobbs Corp. I have no idea what aircraft that might have been, knowledgeable ebay's are welcome to chime in.  Measures ~3in diameter and 2.5in deep.

Please note that seller does not represent that this specific instrument was actually removed from any aircraft cited in the description, but that any documentation referenced here is evidence that it is the same type number and/or manufacturer's part number, used in these aircraft, or if such numbers are not available, the item closely resembles photos of the aircraft's instrument panel.  We do our best to link instruments to specific aircraft, but Buyer accepts responsibility to perform the research to verify the item's use in specific aircraft. 

2BAnAviator is presenting vintage military aircraft instruments from the 1940's, 50's, 60's, and 70's, ready for casual or serious collectors interested in aviation history.  Our inventory includes instruments from aircraft of the US Navy, US Army Air Corps (i.e., pre March 1942), US Army Air Force (March 1942 to Sept 1947) and the US Air Force (post Sept 1947).  Watch 2BAnAviator for many more listings coming soon.

Note that items are sold for collectors.  Unless otherwise specified, seller makes no representation of the item’s serviceability or fitness for use in an aircraft other than for static display.