I suggest Energizer Ultimate Lithium batts. They don't last any longer than alkaline, but they don't leak.
I probably own 10 of @Glock 'em down flashlights! O lights. The key chain ones are loved by many. I gave them as Christmas Presents and this year they hinted they really like the O light key chain lights.
I told ya’ll GED is a Fleshlight Connoisseur!!