What is the Difference in Roller Sizes on Horizon Treadmills?

Our Go Series units (T101, T202, T303) have rollers that are tapered measuring 46mm/42mm. 

Our Studio Series units (7.0 AT, 7.4AT, 7.8AT) have rollers that are tapered measuring 60mm/46mm. 

The largest part of our rollers fit in the center of the frame and taper on the sides to sit in the frame. 

Larger rollers increase the durability of a treadmill as they reduce tension on the belt to help the treadmill last longer.