Voigtlander 21/25mm Viewfinder (Black Metal)

The is a shoe-mounted viewfinder that does double-duty, giving you a bright clear image, with brightlines marking a 21mm lens and a 25mm lens. There's a parallax indicator at 25mm. This viewfinder has a lens with 4 lenses in 4 groups, magnification of x0.42, and a metal body and a metal foot.