ReklinedRider
Zen MBB Master
Hello Taoweiji,Maybe reach out to Customer Support so they can weigh in on the 'grommets'?
See the response to SofRider29. The O rings (they are O rings, not grommets--my mistake) seem to be there to prevent overtightening the clamps. If the clamps are not overtightened, they are not absolutely necessary.
Kline