Lumens Number of lumens is the most basic measurement of an LED flashlight‘s brightness. Another development in LED flashlight technology is the ability to adjust brightness. For instance, some of these flashlight models allow the user to toggle between low-intensity and high-intensity brightness settings. Others feature a dimming capacity. To get specific about an example torch, the Coast HP7 LED flashlight has two brightness options: 58 lumens for applications that demand less light, and 251 lumens for tasks on the other end of the brightness spectrum. The benefit of this design is that you can preserve battery life by adjusting light output according to your needs.
Batteries: Some torch flashlights come packaged with batteries included. A few flashlights are designed to work with rechargeable batteries that are activated by winding or shaking–excellent for emergency kits. A few lights work with lithium or lithium-ion batteries.
Water Resistance tests have three types: Temporary immersion at a specified depth (Water proof), continuous immersion at a specified depth (Submersible), and resistance to splashing from all sides (water resistant). To pass any test the torch must function right after the test and 30 minutes later. The maximum depth for which it passes is displayed in the icon.
Impact Resistance is the height at which a flashlight, with all of its accessories and batteries can be dropped on a concrete floor without being visibly cracked or broken and while also being fully functional.
Reflectors and lenses: A reflector with an approximately parabolic shape concentrates the light emitted by the bulb into a directed beam. Some flashlights allow the user to adjust the position of the lamp, giving a variable-focus effect from a wide floodlight to a narrow beam. Where multiple LEDs are used, each one may be put in its own parabolic reflector. Flashlight using a “total internal reflection” assembly have a transparent optical element (light pipe) to guide light from the source into a beam; no reflector surface is required. For a given size of light source, a larger reflector allows a tighter beam to be produced.