Yeah... It would be nice to have for 20V too.. but the only way now is to DIY a transparent window.
Btw, try imagining how cool it would be to have a transparent valve cover as well... I think Lexan should be able to withstand the heat... but not too sure about it.
I know this question is best answered by a mechanic, but I need to know in advance whether if a damaged air valve itself can be replace by its own or must the entire tyre or entire tube be changed?