This Hop-Up unit is a collaboration between Umbrella Armory and Maxx Model. No modification of the arm will be required if you choose to install this unit into an R-Hopped barrel.
We requested the Hop-Up arm modified to be used specifically for R-Hop setups. The nub is completely flat and it is different from the concave nubs that come with the MEs. This is to ensure the nub is placing pressure dead center on the R-Hop patch itself. This Hop-Up does not support Flat-Hop only setups. This unit should only be used with R-Hopped barrels in conjunction with a Flat-Hopped bucking because the wheel does not allow the arm to protrude as much as the ME models, to prevent damage to the patch. However, this allows for greater degrees of fine tuning on R-Hop Barrels.