They were originally made in Sweden but to the best of my knowledge the only supplier now is Ertec in Danmark. I don’t have their contact details but if you google them all the info is on line.
Hope that helps
Just a heads up on a recent lesson that I learned related to the ports on my NC 33 – vintage 1987.
I have started to see some crazing on my ports both on the aft cabin and the fore cabin. Some research revealed that the port material is an acrylic or poly-carbonate material and should not be cleaned with any ammonia or vinegar based window cleaning solution (like windex here in the USA). The mild acid in these cleaners will react with the acrylic and induce crazing & cloudiness.
Anyway the pilot house is apparently toughened marine glass and not susceptible.
Hope this helps prevent someone from making the same mistake.