Wearing this item will give its user six extra jumps, after which it must refuel for a time. This will help characters with recoveries by flying up when they jump, including those that have weaker recoveries. While equipped, characters' hands are free and are able to pick up other items. Upon its time being worn by a fighter expires, the Rocket Belt will fly off the fighter's back, into the air, and disappear off the top of the stage.
This item is basically two jet engines with a belt connecting them. If you pick it up, you'll be able to soar through the air. It has a limited amount of fuel, but it can recharge when you're on the ground. It's especially helpful for returning to the stage when you've been launched.