Forerunner 110 210
My 500's are the best around, better than new the battery will last all day and night.
This battery is rated a bit higher than the stock battery and performs better than the stock battery. Garmin Edge Garmin Forerunner 305 205.
This battery is the same as the stock battery. If your 310xt won't display anything when connected to the charger, a battery replacement will not fix it.