Features:

It is completely authentic and high-quality
If your garage door is a sectional track style and it is old, noisy, or broken, this roller kit is exactly what you need.
The garage door will open and close more quietly and smoothly thanks to the 13 ball bearings. door hardware that is ambidextrous
Suitable for use with a dust cover (not included, need to buy it separately)

Specification:

Wheels made of nylon, axles from steel
Thicker than average wheels by half an inch.
1 13/16" Wheel Size
It's 4-3/4" long in total.
Length of shaft is 4-1/8".
7/16" Shaft Diameter
Grease-Filled, Regular Capacity
150 lb. for a single load
Equipped with 13 ball bearings
The total number of items per pack is 12.

Included: 

Nylon Rollers for a Garage Door - 12