B&W Viewing Filters

I don't know if anyone has previously mentioned this, but George DeWolfe is selling a B&W/monochrome (amber) viewing filter for $35., basically the same as the one I purchased from Calumet years ago. George's are round, but still, it allows one to preview the scene in a more monochromatic rendering.

Here's the link: Dead Link Removed

I'm planning on getting one in the spring. Thank for the option.