V-groove bearings are made for linear motion applications where the bearing runs along a... rail or track. Why do we care?...BECAUSE WE STRAIGHT TO THE RAIL!
The bearings are sealed to preserve the life span and is rated to spin up to 6,500 rpm's. Why is that important?... BECAUSE WE LIVE LONG AND RIDE FAST!
The RM4-2RS! Get it today! http://www.vxb.com/page/bearings/PROD/Kit8354