Stewart Filmscreen Corp. makes two high gain screens:
Platinum 300 is a 3.0 gain screen with a slight gray cast to it.
Silver 400 is a 4.0 gain screen that is silver in color.
I happen to use the Silver 400 and love it.
Please note on both of these screens there are anamolies in the "silvering" process. What this means is that with a very white background you can see them. They look like "too much" silvering was applied. Mine has a small 6" spot almost at the bottom which doesn't affect me at all.