I had a new Toyota with fixed point roof bar mounts with 890mm distance between them. This seemed to rule out my exsiting roof box but talking to the Roof Box Company I was told that the exsiting roof box could use T slot adaptors that would allow it to be fitted to new Atera Roof bars. The whole kit of roof bars and T slot adaptors fitted together very easily and works well. I would add that the Atera roof bars come ready assembled for the car, and are very quiet without the roof box fitted. Throughout the comapny agents have been very freindly, and helpful by phone or email, and extremly patient too.