Rollei Rolleiflex Hellblau Blue Lens Filter Bay I 28.5mm -Clean-
This is a light blue filter for color correction or lightening the sky in your black and white photography. It is Rollei Bay I (28.5mm) and fits all of the Tessars and Xenars with bayonets.
This is one is in unusually clean condition with clean scratch-free glass. The mount shows very light wear.