Bottom rolling hardware supports the weight of the gate or door from the ground. This is a great alternative for box track and flat track sliding hardware. Bottom rollers can be used for single sliding, bi-parting, bipassing, telescoping sliding, and slidepast applications where the load of the door can not be supported by the building. The bottom rollers are built into the frame of the door or gate. No more or less than (1 Pair) of rollers per door or gate otherwise you get an uneven distribution of the load across the rollers.
Use a top guide system to stabilize the top of the door.