Yes nice wartime one and yes you are right about the extra strap part for fitting around the winter flying suit
Thank you Kradman!. When I was looking at them on the internet, many had no straps at all, and I did not find one with the extra strap.
I am guessing that the bubble should not be there.
nice find Dean.shame about the bubble.
Nice ww2 luft compass with extension strap Kadiac was a manufactuer located in occupied CZ. timothy