This is a large helium tank which will fill approximately 580 11″ helium balloons. This tank holds up to 2400psi of helium (or 291 cubic feet) and an 11″ balloon uses up to 4.2 pounds (or .5 cubic feet) of helium. A 12″ balloon uses 5.1 pounds (or .6 cubic feet), which means you can fill up to 480 12″ balloons with a full tank. We offer helium tank rentals in two different ways. You can either rent a tank for $19.95 per day plus $.15 per pound of helium used or get a full helium tank which you can keep for up to a week for only $250.00 If you are going to use 1500 pounds or more of helium, you are better off with a flat rate. We also carry balloons, curling ribbon, balloon clips, and Hi-Float.