I've seen 3 type of sport earphones so far, there are:
Neckband styles that wrap around the back of your head (such as the Sennheiser PMX 680i)
Earclip styles that hang over your ear (like the Sennheiser OMX 680i)
*Earbud styles * that you stick directly in your ear canal (like the Sennheiser CX 680)
What style should I consider in terms of comfort and ensuring the earphones stay on while for running or jogging?