|Diameter x Length||-|
Mine is a 28 serial number, built by Komine. Actually, I own several.
Common and really cheap on eBay, under $20 including shipping. Slightly soft (low contrast) wide open, but IQ typical of a good 135mm f/2.8 -- and most 135mm lenses are pretty good. My favorite lens to use on tubes/bellows, IQ that way is better than some macro lenses. Built-in shade is nice. Not light, but compact and very well-built solid metal body.
Only annoyance is that lens cap fits over built-in shade, which makes it bump into any filter when the shade is pushed back.