My factory fitted towbar on my X3 is made by Oris. Had some issues as I was only supplied with one key by the dealer and BMW cannot get replacement keys, even though they are listed in the EPC.

Am quite impressed with the build quality of the Oris kit, and their customer service is excellent. I contacted them and they sent me a pair of keys to fit; MUCH cheaper than the BMW listed price too.

It seems that BMW use various suppliers for Factory/OEM fit, Westfalia, Oris and Bosal (Oris are now part of Bosal I believe).