Where to find them?
I prefer free shipping, or low cost ones, thanks.
Diffuser for the BTU? That’s a big diffuser. Maybe try a white traffic cone 
My BTU has a GITD tailcap, I thought they all did. I think it’s a standard 16mm tailcap.
Question about , GITD
Do they actual glow nicely, I bought GITD “O” rings and they are pathetic , I think even a cat would have trouble seeing them.
Most GITD I’ve used fades quickly. After 20-30 minutes, it’s barely visible in the dark.
Oh, so your saying BTU ships with GIDT tail cap from factory - Ric already? that’s great, i still don’t have mine!
And about the diffuser, i think i wont be able to find one, to bad, i would love to have powerful portable lamp (Shocker with diffuser)
Yeah, BTU ships with GITD tailcap, unless it recently changed.
Diffuser with 107mm diameter? Not seen by me.
How about DIY diffuser? 
Someone ever made one? lol
Thanks.