Proven item-transport technology.
Yelling into Quiksilver’s Medium Duffel Bag allows you to summon spirits from beyond the grave—wait, never mind. They were probably referencing the size of the bag. It has a shoulder strap and a Quiksilver logo on the side, and it’s totally rad for carrying a medium amount of stuff. Although yelling into it probably won’t summon anything except a lot of funny looks.