This bi-fold door guide features a durable, spring-loaded 7/8 inch outside diameter nylon roller housed in a sturdy steel base, offering smooth and reliable operation. It is designed for installation on the top edge of bi-fold doors ranging from 1 inch to 1-3/8 inch thick that have a 7/16 inch diameter mounting hole, helping to stabilize the door and ensure effortless gliding along the track. Commonly used on doors weighing up to 30 pounds each, this guide is compatible with systems by popular brands such as Acme, Stanley, and Cox, as well as many other bi-fold door manufacturers. Ideal for residential or light commercial applications, this roller assembly helps restore functionality to folding closet or pantry doors that may be misaligned or off-track. Built to last with quality materials, the combination of the steel base and nylon roller offers both strength and quiet operation. This listing includes a 2-pack for convenient dual-door setups or as a spare for future use.