Are you talking about C and D Alkaline cells in flashlights such as MagLites?
I've often wanted a quick and easy way to load AAs into my Pelican StealthLites in the dark.
SureFire flashlights can have single unit batteries made up of 2, 3, or 4 DL123As. I personally don't need 'em & they're much more expensive than getting them individually.
Alastair