The Hepco & Becker tank ring for fastening tank bags is a big advance for attaching tank bags to the motorcycle.
The problems associated with positioning the tank bag are eliminated by magnetic centering.

The side ribs attached to the magnets also mechanically secure the tank bag. When the lock is released, the poles of the magnets match and the tank bag is released from the attachment. can be attached to the tank filler port. The tank bag‘s base plate shields the magnetic field of the tank ring‘s two permanent magnets, so that credit cards and electronic devices cannot be damaged. 

Facts:

• Special silver powder coated metal tank ring
• Two high power magnets which secure the tank bag on the ring
• Every Tank bag by Hepco&Becker can be fitted; but depends also on bike specific tank-lid positioning and handlebars
• Tank bag "Daypack small" does not need tank rings