The 18650 is a workhorse battery and provides both the higher voltage and current for highdemand applications powering everything from laptops to the tesla model s

18650s require a special charger and a little different handling so i suppose some people would prefer to have a flashlight that uses the a more standard battery or want to commonize with the same batteries as their walkietalkies and other devices

You can use standard alkaline aas though i would recommend rechargeable nicad or nimh or lithium singleuse batteries since this flashlight has a very high current demand on the turbo setting

That said ill be comparing the ea45s to the nitecore p12gt which is an 18650powered flashlight since both use the cree xpl hi v3 emitter and are both rated at 1000 lumens