Theres 4 in each box. One got to be right.Doesn't the little box contain two small (right size for Flexstem) and two somewhat higher elastomers?
I’ve never owned a bike with suspension until 30 days ago and that spans many many many years.For me it is the small conical one that works and the cylindrical did not, but my stem uses an aditional metal plate I see not fitted to your stem.
As devoted rigid bike rider I am not the biggest fan of suspension, but I am impressed by the affordability of this system.