This is a Manufacturer Sourced replacement part for Lawn and Garden equipment. This item is Metal an is Sold Individually. A lock nut is a type of nut that resists loosening when properly threaded onto a bolt. This Locking Nut has multiple uses based on your tool. You would need a Wrench to tighten or loosen this Hex Nut.
The hex nut attaches to the drive case cover. This part is made of metal and is sold individually even though many nuts may be needed during installation. This part may become stripped or lost and will need to be replaced. A wrench will be needed when replacing this part. It is an authentic OEM sourced item which is specially designed for use with Homelite and Ryobi chainsaws.