Will the cap screw on to a standard 20 oz...
Will the cap screw on to a standard 20 oz water bottle? What is the diameter of the cap?
Platypus caps are the same size as standard plastic bottle caps. You will have trouble drinking out of a 20 oz bottle with this hose because the bottle isn't flexible enough. As you drink the water, it will create a vacuum inside the bottle that will keep the water in.