What is the application of this Tandem Door Roller?

Name: CCW ETDR – Tandem Door Roller
SKU: ELC-TL-GA-1
Availability: InStock

This tandem door roller is designed for double-wheel or “tandem” sliding or pivoting door systems where smooth, reliable operation and durability are required. It is listed specifically under “Tandem Door Roller” on the Focus Doors site.