This is the ProTek R/C "Fast Fill 2" 500cc Fuel Bottle. The Fast Fill fuel bottle's 500cc graduated reservoir holds enough fuel to last the duration of a long main event, while the super soft material makes it easy to fill your tank quickly. The molded cap plugs into the spout to prevent spills and keep dirt out of the bottle, and an extra cap is included so you have a backup in case you lose the primary cap. Plus, the bottle/spout seal assembly, includes a cap storage pocket, so you can use it to hold your cap during filling, or hold the spare so its easily accessible when needed.