Suitable for vehicles without roof rail. Not used in vehicles with roof rail. It is used to carry loads on your vehicle. It is necessary for the installation of bicycle carrier, ski carrier, roof box etc. products. The maximum load limit in the vehicle with this product is 75 kg / 165 lb. (Regardless of 2 or 3 aluminium bars, the legal limit is 75 kg / 165 lb.) After the installation of tents etc. while the vehicle is parked, a maximum load of 150 kg / 330 lb for the product consisting of 2 aluminium bars and 225 kg for the product consisting of 3 bars is recommended. The product has an extra lock mechanism after assembly. It is a deterrent against theft. These locks must be opened with a key for disassembly of the product. To confirm the compatibility of the product with other products, please check the technical drawing of the aluminium bar in the listing images. It cannot be guaranteed that it will be fully compatible with any other brand or product from another company.