While this may look like a IV bag that you would see in a hospital it actually something nearly as cool which is to allow proper bleeding of a brake caliper without the mess AND there's no pesky nurse to bug you.
Basically, hook the flexible hose up to the bleeder valve and either hang the bag or just let it hang and give the brake a pedal a few pumps until you see either the fresh brake fluid come through the tube or you stop seeing air bubbles. Hose is 30 inches long and both the bag and hose are reusable.