Lumen Metabolism Fitness Tracker by Metaflow for weight loss LIKE NEW Comes in traveling case Used only a handful of times Charger included Lumen measures the C02 levels in your breath to interpret your metabolism by understanding if your body is using carbs or fats for fuel. Benefits of metabolic flexibility Easier weight loss Better sleep Optimized workout performance The Lumen Device Metabolic tracking in the palm of your hands * Sleek & compact design * iOS and Android app * Golden CO2 sensor * Travel Case Bundle to save more New to Poshmark? Get $10 off your first purchase by using the referral code: @tiffmbmurphy Items come from a smoke-free home Please feel free to ask any questions you may have. Thanks for looking !