Two CRL Laguna Series Anti-Lift Top Rollers are needed for each sliding door panel. These will be placed on the Cat. No. LS104BS Top Sliding Tube after it has been mounted to the glass panels or wall. The door panel is then positioned and attached to the Rollers. Anti-Lift Top Rollers will allow for 1/8" (3.2 mm) up or down adjustment for final alignment. Rollers are supplied with both Surface Mount and Flush Mount Fittings so the glass fabrication choice is yours.