This Sliding Door Roller has a single,
1-3/16 inch (30.2 millimeter) diameter center grooved steel ball bearing wheel.
The housing is 1/2 inch (12.7 millimeter) wide with screw holes 2-1/2 inches
(63.5 millimeters) on center. It fits a 2-15/16 by 1/2 inch (74.6 by 12.7
millimeter) mortise slot in the door rail.
Minimum Order: 1 Package (Two rollers per pack)