The cast silicon steel galvanized garage door pulley with a precision ball bearing runs smoothly and quietly and it solves the 3 main wear-out mechanisms of the standard stamped and riveted zinc plated pulleys. The description of this as a cast iron pulley rather than as silicon steel is a distinction without a difference for the consumer. Both are hard surface iron alloys. For the manufacturer, cast steel can’t be machined on a lathe it has to be ground making the bearing retaining clip groove impossible. The pulley appears to have been made from a steel sand casting and then the casting’s ID is machined for the bearing and the retaining clips and the OD is machined for the cable groove. The completed pulley appears to be zinc electro-plated heavily like a nail or lag screw is. The type 6202 ball bearing is placed in the ID and retained by a spring clip in a groove. I think I would have produced the blanks by sawing slices from a round steed bar rather than sand casting, because the bar can be roll formed, bored, sawn into many, then hardened and plated, but to each his own. The quality of the pulleys is a little less than it might be, but not in any important way. The ID isn’t precise so there’s a little wobble. On the plus side the ball bearing can be replaced without having a press. The centering of the casting in the machining is off by several mm. That’s harmless, just visually distracting on close inspection. This construction will not suffer the most common causes of failure of the common stamped riveted pulleys. The cable in the groove of that type is always pushing the 2 stampings apart and it eventually succeeds. As it goes around, the rivets on that type are wiggled and stretched and the plates flex apart. Eventually the cable wedging into the gap pulls a rivet apart. The ball bearings run on a center race, but the outer race is just the stamped sheet steel. When the rivets stretch the ball bearings also wedge the plates apart and the pulley gets wobbly and eventually jams or drops the cable. If the rivets hold up, the hardened chrome steel ball bearings gradually re-shape the soft stamped steel outer race until the ball bearings open a hole and jam or the pulley wobbles enough to drop the cable. The thin zinc plating of the stamped pulleys is susceptible to corrosion but that’s only of concern in salt air at the coast.