Together with the custom red flags, we will be using an environmentally friendly, temporary red spray to mark the course with an S (for Swiss), an arrow, and an A (for Alps).  Our 100KM runner Andreas Manz recommended, that we should use a reflective spray for course markings. That way, runners will see the arrows in the dark, because they're very light-reflective. We found this to be a very good idea and Albedo 100 Reflective Spray has the perfect product for that.  So all runners, who are… Albedo, Red Flag, Swiss Alps, Arrows, That Way, Flags, Runners, The 100, Dark