First of all you must identify your vehicle type to define the corresponding range. There are three main families:

• Classic: for vehicles not originally equipped with side bars
• Railing: for vehicles originally equipped with side bars
• Pro: for utility vehicles

You can then choose the product which corresponds to your need (aluminium, locking system, fix point, etc.).
Lastly, you simply have to check in the Automaxi guide the reference which corresponds to your vehicle (make, model, year, number of doors).