Hiding the center seat belt under seat

[L-Altos]

Those of you with an E90 know that the center seat belt can attached to either its receptacle in the seat, or it can just insert itself into the plastic block on the rear deck. Either way, it is annoying for passengers since the receptacle pokes most people in the back making it uncomfortable to ride in the seat behind the driver.

Given this problem, and the fact that i cant ever see using the center belt, I decided to just leave it under the seat. Now it looks better, and there is no more annoying protrusion.

When I had the rear seat out i noticed that there were a couple of long metal tubes under the seats so I made sure that the seat belt was positioned away from them. Does anybody know what those tubes are, and does the seat belt interfere with them?