This is the same type of sight that was used in the P-61 as well as some P-38's but I can't recall what the specific designation of the sight was. The L-1 and the G-1 are nearly identical but I am not sure if the L-1 has the knob.
There was also a post war aircraft that used this kind of sight too but that also escapes me. Trouble with getting old!
I will look it up later when I am back at the shop.

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