This flashlight battery have the similar concept as the Little Lamp, elevating the small battery to light up a LEDs so you can use it to light up your surrounding.
“We think these three bulb LED flashlights are a fine idea for a diminutive and temporary light source…like one of those keychain lights but x3.”
— by UnPlggd | Apartment Therapy
Using 9V battery as the source power to light up 3 extra bright white LEDs. The installation is extremely easy. Just locate the size of each hole and plug it in accordingly, and… your flashlight is ready!