The Duo Bone Conduction Health-Monitoring Earphones take bone conduction technology to the next level. Rather than simply acting as headphones, these bone conduction earphones have a Na+ ion sensor that monitors your hydration. Additionally, these health monitoring headphones can even keep tabs on your metabolism. So if you enjoy sports and activity, the Duo headphones can help you keep tabs on how you’re doing. Though they’re just a concept design for now, these earphones also have add-ons. For example, the Aid Loop can help users better hear sounds in their environment. And the Glass Adapter lets you wear the headphones comfortably with glasses on. These earphones really have it all: you can share audio with others nearby, and you can even monitor your heart rate. The Duo is an integrated smartphone, activity tracker, and headphone device.