You must be logged in and verified to contact the designer.
Valve cap that fits a Schrader valve (such as used for bicycle tubes or car tires) that forces the valve open when screwed on. This makes it easy to get all the air out when you want to deflate and fold the tube. It comes as a set of 4 pieces that needs to be cut apart before using.
When you use it for the first time screw it on carefully and make sure that it goes in straight because there might be some of that plastic powder left in the threads.