Peak makes a version of the Baltic Sea that utilizes 2 LR44 button cells.
the light is a twisty and uses a Seoul P4 and is only 1.6 inches including the lanyard attachment. the pocket version is 1.5 inches.
you can get it in brass, ss, or haIII..or a combo. i have a baltic sea brass head sp with HaIII body and brass tail with an N cell.
2nd to bottom on the left has the low profile keychain attacthment. i wish
peak would offer this style on their larger edc lights.
I'm not sure how bright it is on button cells or which power mode you should pick, but if you call them, they will recommend a level based on your needs.
see this thread for more info and pics.
https://www.candlepowerforums.com/threads/212589