This standard solid nylon roller (individually) is the most common wheel used by door manufacturers and installers. They are made of solid nylon for quiet operation, and roll smoothly. They are perfect for replacing old, worn, noisy, or broken rollers. The 4 in. stem is suitable for standard single-hinge installations. The average residential garage door has 10 rollers on it. For smooth and easy opening and closing, and to extend the life of the electric door opener, change all rollers at the same time or when adding a new electric opener. Always work carefully and secure the door before starting your replacement.