[slacktide]

I thought these looked familiar, I have product that uses them, but a version with dual LEDs. The CFFA3000 hard drive / floppy emulator for the Apple ][ used them in a floppy disc control panel.

https://shop.dreher.net/shop?olsPage=products%2Flimit-3-per-...

http://dreher.net/?s=projects/CFforAppleII&c=projects/CFforA...