I am using the CX680 for over a year and half. The fins were useless to me to keep the buds whilst running, but instead of buying overpriced Sennheiser replacement silicone tips, I have used disposable foam tips. They do not fall out whilst running and provide excellent external noise isolation...

  I am using the CX680 for over a year and half. The fins were useless to me to keep the buds whilst running, but instead of buying overpriced Sennheiser replacement silicone tips, I have used disposable foam tips. They do not fall out whilst running and provide excellent external noise...