How many lumens of flashlights are suitable for slingshots?

600 lumens. Lumen is a physical unit to describe luminous flux, which is used in flashlights. 600 lumens is enough for outdoor slingshots, so it is more appropriate to use a flashlight with 600 lumens for slingshots. A flashlight is a hand-held electronic lighting tool. A typical flashlight has a battery-powered light bulb and a focusing lens, and a handle-type housing for holding. Although it is a fairly simple design, it was not invented until the end of 19, because it must combine the invention of battery and light bulb.