What does the back look like? Casual inspection of the front face won't tell you if if was:
a) AC Cars from the Cobra production period.
b) AC Cars from the 428 Frua production period and service for all cars
c) Valley Ford Parts reissue/reproduction of the 428 Frua version
d) something else
a and b were retained by three tiny spring steel clips with sharp grip points. C uses the same type clip. The Valley Ford Parts are still being sold new with three clips included.
Original of (a) are very rare without damage to one or both sides even if just the tiny hair line fractures that years of exposure create in the lens over the AC script. Original (b) are pretty rare but not as rare as (a) because AC Cars provided them as service parts for years post production.
The pictures in this ebayŽ offering (not mine) looks like it could be the Valley Ford Parts version.
https://www.ebay.com/itm/AC-Cobra-Le...0AAOSwMmBVmjHH