This is a replacement dishrack roller or wheel for your dishwasher. It is made of gray plastic, measures a little over an inch in diameter, and is sold individually. This roller is designed for the lower dishrack of your dishwasher. On one side of the roller is a clip that allows it to be attached to the dishrack. The dishrack roller allows you to slide the dishrack in and out of the dishwasher efficiently. If one of the rollers is broken or missing, it can cause the dishrack to become difficult to slide in and out. To replace the roller, simply snap it off the dishrack, and snap the new one into place. This is a genuine OEM part.