I picked up several on sale 4 packs of AAA Lithiums at Office Depot. $ 4.01 per pack. Great deal. Never used them before cause I wasn't about to pay retail ($ 9.99 per pack).
Popped one in my new Matterhorn Hi-Power AAA/3LED, and WOW, what a difference. My eyes say 100% brighter.
Also shouldn't have that "sag" after some run time.
Happiness is a bright, white light.