RCA Projection TV in Central Europe

[centurion]

Projection TVs are completely unknown in my country. I bought the first one a few years ago. More appeared after it. One of the most interesting and most damaged by moisture is RCA 9PC41. I've had it for several years. I recently discovered that CRT has good emissions. I started its renovation. So far everything is going smoothly. Currently, I have my first technical question regarding the high-voltage capacitor. What is the brass ring on one of the capacitor poles for?
Greetings from Poland

Adam