For all models with the QL2.1 system. Inserts are available for the two upper 16-mm mounting hooks that come with the proven QL2.1 mounting system. The inserts allow you to securely attach your ORTLIEB pannier to virtually any bike rack with smaller tube sizes (16 mm). DETAILS (PER PANNIER): - 1 pair of 8-mm inserts - 1 pair of 10-mm inserts - 1 pair of 12-mm inserts