When his new bone conduction earphones came, Dad let me take them for a run. The Bluetooth Mi TWS S03 has a curved hook designed to hold it in place. Long story short, it worked. I did get the feeling of slippage at times, but the curved hook made it feel firmly attached. The <$10 price also made me less anxious about losing them.
The sound quality was not too shabby, though it’s nothing to write home about. The biggest flaw I found is the battery life. It went from 87% to <20% after just three 40min runs. Its lack of noise-cancellation also means I have to stay off big streets; on Miller or De Anza, cars rushing by can be surprisingly loud.