The Giant Disk was a type of Promotional Nerf ammunition that was designed and made for use with the Captain America Disc Launching Shield. No refill packs can be found. Although the Zip Shot's Foam Disks look quite the same, they aren't compatible. So far the Captain America Disc Launching Shield and the Arc FX Gauntlet are the only blasters that can fire these types of ammo, but the Gauntlet's disks are a bit smaller than the Captain America Disc Launching Shield.