RGW 30 CC ZAH HIWIN
the RG series is a type of linear guideways that uses rollers as the rolling elements.Rollers have a greater contact  area than balls so that the roller guidways features higher load capacity and greater rigidity.The Figure shows the rigidity of a roller and a ball with equal 
volume
super high load capcity- with the four rows of rollers arranged at a contact angle of 45 degrees the RG series linear guidways has equal load rating in the radial,reverse radial and lateral directions.

The Rg series has a higher load capacity in a smaller size than conventional ball type linear guideways.