The transport capacity can be increased from 2 to 3 bikes by adding adapter 973-23, and by adding both adapters 973-23 and 973-24, it can be increased to 4 bikes. The elevated position of the carrier maintains visibility of the taillights and license plate. All parts that come into contact with the vehicle or bikes are covered with protective rubber. Convenient loading of bikes is facilitated by removable bike hold arms. Secure bike attachment is ensured by rim hold straps with quick release. Extendable wheel rails accommodate larger bikes. It folds flat for easy storage and handling. It secures the bikes to the bike carrier (lock included) and the bike carrier to the vehicle with separate accessories. A vehicle-specific mounting kit is required for installation on different vehicle models. This product is not universally mountable. Please use the Thule buying guide for information on specific car models.