- Flashlight LED (look for the best LED out there that a flashlight uses and filter flashlights using that specific LED)
- Power source (I recommend 18650 batteries)
- Does it come with a battery?
- Can you charge your battery without taking it out or does it come with a charger?
- Features useful to you (Water resistant, Impact proof, Other features such as clips, carry bags, or holders, depending on your needs.)
To get you started on understanding flashlights, LED’s and lumens. Here’s some videos.
18650 Flashlight Reviews | BudgetLightForum.com