This Spool Cover has been designed to hold your spool in place while your trimmer is in use. Easy to use - simply remove this spool cap from the trimmer head by pressing on the side tabs. From time to time you may need to replace your trimmers spool cover, due to general wear and tear or if you accidentally catch the spool cover against a wall or stone. Your trimmer will not operate properly if your spool cover is not secure.Please check model fit list to ensure this part is correct for your model.