Replacement funnel for Mediflow Water Pillows. Just like the original, it both twists open the pillow's cap and helps fill the pillow with water. Watch me accidentally make a mess while filming myself demonstrating:

You'll need to use a small pair of pliers to carefully remove the supports, as they surround the funnel's threads. There's also one teeny-tiny support in the small hole inside the funnel, you can just use a toothpick or something to poke that one out of place.