This genuine replacement part is an extension spring for use with a self-propelled lawn mower. This part is essential to the proper operation of the lawn mower. This part is an identical replacement for an original carrier extension spring that is damaged, faulty, or missing. If the lawn mower blades won't turn, the most common reason is a faulty extension spring. The extension spring attaches to the idler arm and the spring return hook. The purpose of this part is to apply tension on the guard, allowing it to retract.This OEM replacement part is sourced directly from the manufacturer, and is sold individually. This part is made of high quality metal. For installation information, please refer to the original product manual and follow all safety precautions. Pliers are required for proper installation of this part. This part is compatible with a variety of MTD, Troy-Bilt, Craftsman, Yard Man, Columbia, Craftsman, and White Outdoor lawn mowers.Please note: original part numbers 2394165, 732-04826 are now obsolete, and manufacturer has replaced the original part numbers with this part.