This is a nice automatic chronograph, even with flyback function.
Reference Citizen 67-9071, aka Monaco. It came also with a yellow dial.
The case is made of a black coated alloy with a stainless steel hood and stainless steel caseback. Citizen calls that BLS.
I own one of these and it is running very good. I think case size is 38 mm x 42 mm. It has 18 mm lug size.
It has no permanent seconds, so you can only hear if it is running. Usually I let the chronograph run all the time to get visual feedback.
The pictures are not good enough to really see the condition.
The edges on the polished top seem to be fine but it is difficult to judge the black coated parts.
In any case, it requires more photos of the movement and case back.
Here is a link to a nice documentation of a restoration project:
https://sweep-hand.org/brians-restorations-the-citizen-67-9071-monaco/
Here is a nice overview of the 8100A and 8110A chronographs. Scroll down for 67-9071:
https://sweep-hand.org/citizens-vintage-chronographs/Click to expand...