Caution here. I replaced the lenses and gaskets on Ohana last year immediately after we bought the boat, I purchased the material from CD (because I didn't know better....

) and found the following.
The new gasket material for the Lewmar opening portlight (size 1) is just a wee bit thicker than the original gasket material from Lewmar, the reason for this is that Lewmar no longer makes this gasket so it is now made by another company and doesn't match exactly. Not a big deal one might think...unless you couple that with new "upgraded" lenses from CD as well.
The thicker gasket coupled with the slightly thicker "upgraded" lenses make closing the port almost impossible. I had to put my back against the mast to get enough leverage to close those suckers....but they did seal up!!!

I was hoping the gaskets would "seat" a bit and make closing the port easier...but that didn't seem to be happening and we used those nice opening ports less and less.
I finally reached out to CD about this issue and when I explained my problem to the tech guy he immediately stated that I needed to shim the hinges on the ports to ease closing them....this was a clear indication to me that they'd run into this problem before and this was their solution.
In the end I did end up shimming the ports and it did make closing them much easier. I do think that CD should mention the thicker gasket on their site though, I didn't find out about that detail until I was talking to the tech specialist and realized what I was up against.
My recommendation would be that if you want or need new lenses
and gaskets that you should only buy the replacement Lewmar lenses, they are a bit thinner and will probably work with the new thicker gasket if you have to replace that too.