Material
Most manufacturers produce tactical flashlights from multiple materials, such as aluminum, anodized aluminum and plastic. Aluminum is superior to plastic, it provides strength and lightness advantages. Anodized aluminum provides an additional layer of aluminum oxide which toughens the flashlight against scratches and scrapes. These types of materials make sure the flashlight is durable in tough conditions and ensures you are provided with light when most necessary.
Weight, Purpose and Ergonomics
A tactical LED should be lightweight, so you can carry it around for extended periods of time and maneuver with it easily. Some flashlights can be mounted on a gun, so if you need one for hunting, you should look for a flashlight with this property.
Lumens
The more lumens a flashlight can generate, the more brightness it can produce. Higher lumens also means a higher cost for the flashlight. 50 lumens are enough to reveal an area. Flashlights used for searching, rescuing and other purposes that require long-distance lighting should have at least 200 to 300 lumens. For self-defense against burglars, 500 lumens are sufficient to cause disorientation.
Battery Type
Tactical LEDs require a considerable amount of energy to function properly. There's two types of batteries to choose from – disposable and rechargeable. If you go with the disposable batteries, you need to have plenty of back-up batteries for replacement. Rechargeable batteries on the other hand, can function for quite a while, but require an electric plug to be charged. So a good idea is to bring a set of rechargeable batteries, and a set of disposable batteries just in case.
To conclude, there are many types of tactical LEDs to choose from, you should narrow down your decision depending on the features you want it to posses, the amount of lumens you want it to have, the battery type or if you want it to be mountable on a rifle or not.