Maglite
Most Maglite parts are made from anodized aluminum. There is a chrome-plated plastic reflector inside an aluminum housing at the top. Underneath the reflector is the light bulb or LED, which is attached to an aluminum tube. The batteries are inside the aluminum tube. A screw-on aluminum cap with a chrome-plated steel spring on the bottom of the flashlight holds the batteries in, and is unscrewed to replace the batteries. The spring is also the connection to the negative terminal (anode) on the batteries. There is no wire carrying the current to the bulb at the top of the flashlight - the aluminum tube is the conductor. On the smaller flashlights, the flashlight is turned on by slightly unscrewing the flashlight head. The larger flashlights have a push-button switch on the side of the aluminum tube.