The Einstein™ 1500 FLEX Headlamp by NEBO is a low-profile, compact 1500 lumen headlamp with 5 light modes featuring flex power.Use the included rechargeable battery or 2 x CR123A batteries.5 LIGHT MODESTurbo (1500 lumens): 30 seconds / 64 metersHigh (750 lumens): 2 hours / 35 metersMedium (250 lumens): 6 hours / 25 metersLow (10 lumens): 18 hours / 8 metersRed COB (5 lumens): 12 hours / 1 meters*Runtime is reduced by about 20% when using 2 x CR123A batteriesDESIGNCompact and lightweightDurable ABS plasticSmart Power Control (SPC)Water resistant (IPX4)Flex PowerDirect-to-RedOPERATIONTop-positioned buttons for power and mode selectionACCESSORIESLi-ion 18650 rechargeable batteryOne size fits all head strapUSB charging cableBATTERIESPowered by 1x Li-ion 18650 2200mAh 3.7v or 2xCR123A batteriesSPECSWeight: 173 gramsdimensions (L) 12.7㎝ X (W) 5.08㎝ X (H) 7.62㎝The EINSTEIN 1500 FLEX Headlamp features Flex-Power, high-power 1500 lumen Turbo Mode, 4 additional light modes, Direct-to-Red and a two-way adjustable head strap.LIGHT MODESMODES LUMENS HOURS METERSTURBO 1500 30 SEC 64HIGH 750 2 35MED 250 6 25LOW 10 18 8RED 5 12 1OPERATIONA top-positioned button controls the power and light modes.DIRECT TO REDWhile OFF, press and hold button to activate Direct-to-Red. The next button press (within 8 seconds) cycles through the light modes in reverse (RED • LOW • MEDIUM • HIGH • OFF). TURBO MODEWhile ON, press and hold button to activate TURBO MODE.CHARGINGUnscrew the battery cap cover. With the USB cable connected to power, plug the USB-C end into the positive ( + ) end of the battery. Charging indicator glows red when charging; green when fully charged. ADJUSTABLE HEADSTRAPSimple, convenient adjustability for any size.