Aluminum alloy casing * Cree XM-L T6 LED Bulb * Voltage input: 2.8v-4.2v. Powered by 1x 18650 3.7v battery * 5 Modes: High, Medium, Low, Strobe, SOS (Lightly push the tail button to change modes) * Size (mm) : approx 132( length ) x32( head diameter ) x 25( body diameter )