The TE5H20 is a neon indicator from the 1930s.
The Osram name and one of the locating pips for the bayonet base.
The BAL716 stamp shows that it was made to the German Luftwaffe standard and inspected at that particular office. These codes were in use from 1933 to 1945.
The thin glass tube envelope is 15 mm in diameter, and including the base pins is 28 mm tall.
Updated April 19, 2019.