This is the earliest version of 1000mm f11 Reflex-Nikkor mirror lens. It was launched on Oct 1966. The serial number starts from No. 111001 and the earliest lens registered is No. 111036. This lens of No. 111037 is the 37th production lens and the second earliest example ever recorded.

 

Only around the first two thousand lenses were marked with "Nippon Kogaku". "Nikon" was used instead in the subsequent production.
There are four built-in filters . They are L39 (UV), Y48 (Yellow), O56 (Orange ) and R60 (Red).
The rotating built-in filters housing makes the lens very bulky. It was replaced with a more practical screw-in rear filter system in later versions.
 
   
     
5-Feb-2021