http://www.king-cart.com/cgi-bin/cart.cgi?store=elektrolumens&product=Anglelux-XPG&cart_id=1057803.13434&user-id=&password=&exchange=&exact_match=exact
"Alkaline batteries will work but be about 1/2 as bright, in the high power application flashlights, like the drop-ins, Ultra-Throw, etc."