For sale is a gently used, but in excellent condition, Leica USQOO E58 Red filter. This filter was originally designed for the Summarex 8.5cm or the Hektor 12.5cm lenses, but it's a 58mm thread, so it would work with any lens that uses that thread size.
The glass of the filter has some dust on it, but it is free of any scratches or haze.
Please take a look at the photos and ask if you have any questions.