How do you know if a device can use a 3+ volt Battery?

[Chief-A-Lot]

Does it not really matter, as long as the housing fits them in there? I did see a couple modded flashlights with some pvc added to tighten the fit... Sorry for the questions, just wanna get things striaght before I attempt my 1st mod

 

[TnA]

Chief-A-Lot....you are correct. The only thing that matters when considering a flashlight (or any other type of battery holder) to mod is that it is large enough to hold whatever size battery you intend to use. With the mods that used a sleeve, that was because the flashlight tube was too wide for a given battery size and the next size up in diameter would not fit due to length of that battery. Good luck w/ your modding!