The two black hooks are part of the Basil Hook-On system. Do you already have a Basil pannier and would you like to replace the hooks? Then choose the hooks of the Basil Hook-On system. The set consists of two hooks that you can attach to the existing Hook-On system. The hooks can be adjusted in multiple positions on the system, making them suitable for many carriers. The hooks themselves are suitable for a tube diameter of 16mm. Set of two hooks. Suitable for a tube diameter of 16mm. The hooks are part of the Hook-On system for attaching single panniers.r.