2″ Steel Roller with 4″ Stem, 10 Ball Bearing. Deep grooved machined races. Bulged shoulder. Rating: 75lb load: 15,000 cycles of a 12′ door.
Steel rollers are standard with a lot of garage door manufactures, they provide good life and good service for your door.
If you are looking to make your door super quiet, low maintenence, and longer life then look to changing you rollers to the 13 Ball Bearing Seal Nylon Roller with 4″ Stem.