The names DTR and STR tell you where they go and what they do. DTR stands for Down Tube Right side entry. STR = Seat Tube Right side entry. This side-loading design is a great match for our Mandible cage and was developed over a two year period, including testing in MTB World Cup competition. A bonus feature is the extra set of mounting holes that are 20 mm lower, giving you extra clearance from the top tube. Weight: 25 grams Finishes: UD Matte or Glossy 3K Matte or Glossy