1-3/4 Inch nylon garage door rollers with 4 inch Stems 12 Pack High quality nylon shells and steel wheels with zinc-plated finish ,durable and strong It's consist of a combination wheel and axle,and guide the garage door through the track system Home Master Hardware rollers are easy to installed on either side of your door and reduce your garage opening and closing noise by up to 75% Replacement rollers for residential and commercial garage doors.Note:1-3/4" nylon rollers have no bearings