Katadyn Befree Adapter for Platypus Big Zip

With this adapter for a Katadyn BeFree soft bottle you are able to squeeze water directly into your Platypus Big Zip bladder, so you don't have to remove it from your backpack to refill it.
It uses a standard bottle cap with 28mm thread, so it will work for any squeezable soft bottle with such cap.

To make this, you need the cap from any regular bottle with 28mm thread, which you then need to cut a 12mm hole in the center of.
To ensure a tight fit you need a 16mm rubber ring, which fits into the groove on the adapter part.