RPM Revo and T/E-Maxx Replacement Oversized Bearing Set Outer bearings are 6x15x5mm (stock is 6x12x4mm) Inner bearings are 12x21x5mm (stock is 12x18x4mm) Wider bearings create an additional 2mm of contact with the axle for smoother, longer running performance 3mm. larger bearings have balls a full 33% larger than stock The load ratings of RPM oversized bearings are double that of stock bearings and more than triple the fatigue rating of stock bearings as well!