Could you please help me with the crown? I have these buttons, but what does that 9/24, 9/28 etc means? 9 or 8 are the thread size right? 9 is 0.9mm? But what is /24 and /28 and /30? Would that be 2.4 2.8 and 3 mm? I tried to compare a 9/24 to a 9/30 but the 9/30 does not seem to be bigger in any dimension? Not even sure if the right sized buttons are in the right container. I am trying to find a silver button for the silver case. Would be nice to know how the original looked like.