I'm pretty sure it's just glow int he dark tape Dave. You can "charge" it woth a flashlight or whatever and it gives enough light to keep your pin visible.

I've used the Impact Cosmic. My fav apeture but the slide is kinda janky.
Cobra EZ slide...not enough adjustment vertically on the bar for me.

HHA haven't tried.

I found a great deal on a Savage Quick click though. Interchangeable apetures/pins/heads...seems the most versatile to me.

No idea though...heck it may suck