The Nebo Einstein Duo 400 is a headlamp from Nebo's Einstein range, with a maximum output of about 400 lumens according to the model name. The Einstein headlamps are compact, lightweight designs meant for camping, hiking, fishing and working in the dark, worn on an adjustable elastic headband so both hands stay free. The "Duo" in the name suggests two light sources, typically a spotlight for distance and a wide floodlight for close work. We could not find the full specification for this exact version, so check the packaging for the light modes, runtimes and whether it uses a rechargeable or disposable battery.