This Ball Bearing is an individually sold, silver/black, metal part. It reduces friction in the spindle assembly between the spindle shaft and the spindle housing. If broken due to wear/fatigue, you will hear a grinding, growling, rumbling or screeching sound, and should replace the part. Refer to your make, model and diagrams to ensure this is the right part for you.
This is an authentic Simplicity replacement part. The idler pulley is designed by the manufacturer for use in lawn mowers and snow throwers. This part is made of metal, and is used to adjust tension on the V-belt. You will require a wrench when replacing this part. This item is sold individually.