Upload & Sell: Off
Nope. Are they MC? If not I would trash them.
Perhaps the brand was not so Popular after all.
Not sure to be honest. There's nothing on the ring other than what I've already posted. Seems well built though. But that doesn't mean anything. I'll have to do some with and without comparisons when my adapters arrive. Having high hopes it's decent since it was made in Japan, probably around the late 70's. The other filter is a Hoya 1B Skylight. I know Hoyas decent, so I'll be keeping that one.