HCE Filter, Green #1 = #11?

I couldn't find definitive information on this... Is this brand of filter decent? I have one in 67mm, it's not marked MC so I assume it's not multi-coated? It's marked #1 but seems like a normal 11, are they the same?

Maybe.
It's possible that HCE has decided to flout convention & provide their own values. Or perhaps there is no real standard. B&W and Nikon also do this.
I guess it's just to make life more interesting.

HCE filters were made by Tiffen in Japan, as far as I know. So they are "name brand" but also retro, maybe from the 70's or 80's ? So I'm guessing they are single coated, I'm guessing "HCE" stands for "hard coat enamel" or something like that. Like a tough single coat.

If I was looking to buy a filter, I'd go with a newly manufactured Hoya filter. They have the latest technology relative to digital cameras. Like thinner filters, multi-coated, and so on.

I'm no expert though

Greets from Maine,
Craig