Loads of earphones are supposedly designed for running, but have tried loads and they constantly fall out. These are flexible and comfortable and you can mould to your ear shape. On my second pair now and the bonus is they are cheap!!!

I've tried a number of earbuds and a pair of Philips in-ear headphones and always have had problems with ear soreness and poor fit. I picked these headphones up because they were inexpensive but have been very pleasantly surprised. They fit well, sound good, and never fall off.

they're great