These are medium-sized tomatoes on determinate plants. "Treff "means "club" as in the card suit, but I am not sure where or how the name originated.
We received and grew this in 2014, but were unable to save enough seed to offer for sale until this year. There is a heavy concentration of fruits, which remain hard green until late in the season, and then start to turn in a flush of a few weeks. Nice for slicing, better for cooking/processing.