Here's a nice used, but like new COATED Rollei red filter in excellent
condition, in its leather case -- also Rollei. It's marked 39Ø, which
I believe means 38mm barrel size, so perhaps it fits the f2.8
Rolleiflex? You Rollei people will know.

This is a beautiful filter with anti-glare coating for maximum
contrast, which I believe you can see in the picture above. It's a
deep red color -- I would call it Wratten #25A -- which gives dramatic
skies in B/W.

http://cgi.ebay.com/ws/eBayISAPI.dll...m=330018348636