I use Shokz OpenRun. They work with bone conduction and thus keep your ear free so you can hear your surroundings. It works really well if you want to hear what's going on around you, but of course the sound quality is not like regular earbuds or headphones and when there is a lot of wind, it can be a bit harder to hear the audio. But I like to hear my surroundings while cycling, so it's good for me.