I used the adhesive mount and not the clamp for our helmets. I also used a prep/primer that I bought at an auto refinishing store made by
3M. I used an alcohol swab to clean the side of the helmet. I then located where I wanted the Sena unit to sit behind the visor slide bar and traced the outline of the adhesive mounting bracket in pencil. I applied the primer as per instructions that came with the primer (you can google it download the instructions from 3M also). Next peal the adhesive tape cover and firmly squeeze/hold the mounting plate onto the side of the helmet for about one minute. Within ten minutes it is firmly bonded to the side of the helmet and will not come off (a common complaint of some users on other forums).
Using the adhesive mounting plate is essential for the Schuberth helmet and especially the new Pro version with the integrated antenna for the Schuberth BT collar. The bottom of the helmet is not thin enough for the metal clamp to fit properly. YMMV