Hi Dave & welcome.
I "modify" the normal pre-focus globes & fit a 5mm red LED, complete with dropping resistor into the bases.
Can be used in any torch with 2/3/4 batteries.
All this for the lowly cost of just $5 per globe.
I use the cheap "Acme" brand 2 x AA cell from Woollies.
They are very small & you can hold them in your mouth if 2 hands are needed.
There's an article or 2 in here somewhere.