This Carl Zeiss Biometar 120mm f 2,8 MC is a super wide aperture lens for available light photography. The focusing screen is brighter than with anything else in this focal range.

Lens pictured has multi coating and was customized with a Rollei bayonet VI front to accept Rollei lens hood and filters. 

Picture quality is as can be expected from a Carl Zeiss Jena lens, very good but not up to the quality of Carl Zeiss Oberkochen (the makers of all other original lenses for Rollei).