A. [High Performance and Durability] Garage door rollers are designed to offer good performance and durability, making them a reliable option for your garage door. They have reinforced 6200ZZ bearings and transparent dust covers to prevent dust and dirt from getting in, ensuring efficient operation. B. [Ultra - Quiet Operation] Our garage door rollers are made of 1.8 - inch nylon material to ensure relatively quiet operation. This means you are less likely to be disturbed by annoying noises when opening or closing your garage door. C. [Compatible with Most Garage Doors] Our nylon garage door rollers are compatible with a large number of residential garage doors, including standard garage door tracks, wooden automatic door tracks, etc. You don't need to worry too much about compatibility issues when installing our rollers. D. [Smooth and Well - Sealed] Our garage door rollers can reduce the rotational friction between the roller and the shaft, making the opening and closing of the garage door smoother and quieter. Additionally, the sturdy housing of each roller helps prevent dust and dirt from entering the bearings, ensuring relatively smooth operation and potentially extending the service life. E. [Rigorously Tested] Our garage door rollers have been tested rigorously to ensure good performance. In a 160 - pound load test, they can operate for up to 100,000 cycles. You can have some trust in their reliability and durability. F. Material: Nylon G. Color: Blue H. Package Contents: - 12 bearing rollers I. Only the above package contents are included, and no other products are provided. J. Note: Light reflection and different displays may cause slight color differences between the items in the picture and the actual product. A measurement error of plus or minus 1 - 3 centimeters is allowed.