All EVP.MOde Spec TAPP primaries are calibrated with +2mm rollers. Bigger rollers make the low end "quicker RPM's" but shift out quicker and lower the full shift RPM. This has to do with the angle of the arms combined with the weight difference of the rollers.

• +1mm Rollers - Outside Diameter 16.5 mm with a weight of 12.5 grams each.
  
• +2mm Rollers - Outside Diameter 17.5 mm with a weight of 15.3 grams each.
• +3mm Rollers - Outside Diameter 18.5 mm with a weight of 18.5
• +3.5mm Rollers - Outside Diameter 19mm with a weight of 19.7

IMPORTANT - As with the ramp angle roller size must be done in pairs across from each other, failure to do so will result in an imbalance of the clutch and possibly failure.