Ever the stereo enthusiast and clever inventor, Seton Rochwite developed - and manufactured in his own workshop - a limited number of polarizing units. It would be nearly impossible to improve on his design. Not only are the two lens filters linked, but so too is the filter on the viewfinder lens. One could see the effect the filter would have through the viewfinder. The unit replaces the original bakelite lenscap assembly and is hinged so that the polarizers may be swung up out of the way when not required.