Red plastic opto filter for 7 seg LEDs?

[Yorkie]

Thanks for reading my post Andrew, and for your helpful suggestions. In fact for the particular purpose for which I thought I needed it, I don't! It's for the cheapo capacitance meter that Alan Beckett built, and having now built my own kit and examined the display, it isn't separate 7 segments but four in a single unit with the segments all surrounded by black resin so the display doesn't really need a 'window' of any kind - just a hole in the front panel.

I guess therefore that this thread can be closed!