This is a precision made anodized (blackened) aluminum screw-on camera lens cap for Rollei 35 series cameras. Its diameter is 30.5mm and fits all Rollei f2.8 aperture Sonnar lenses. It does not fit for f3.5 Tessar, Xenar or Triotar lenses. Please check my other listing for a cap for f3.5 aperture. Hundreds sold since 2011. Free shipping to all destinations by fast airmail. Please note that my Rollei 35S camera shown in the photo is not included.