Our bike bags come with 16mm hooks as standard. If your luggage rack has thinner rack struts and the hooks are therefore too loose, you can use the inserts supplied to adjust them to 12mm, 10mm, or 8mm tube diameters. The 16 mm hooks are available with a rubberized plastic handle (E212) or with an adjustable handle (E192), which are featured on the Office Bag, Commuter Bag, and Downtown models. If your luggage rack struts have a larger tube diameter and the standard hooks supplied do not fit, you can simply replace them with our hooks for 18 mm (E211) or 20 mm (E193) tube diameters.