I originally purchased bone-conduction headphones to be safer when running. Bone conduction headphones don’t go in your ears like buds; instead, they sit just in front of your ears so you can still hear what’s happening around you. For years I would wear my noise-canceling headphones on the subway, walking to/from the office, etc., but it wasn’t very safe to have all noises completely blocked out. Now, as I roam through cities, take short public transport, and even walk through the airports/train stations, I use bone-conduction headphones instead to be more aware of what’s happening around me.
The Aeropex Mini headphones weigh next to nothing, has excellent battery life, is waterproof, and is loud enough to hear even the quietest podcasts when walking or running through a city.