Nokia BL-4CT/ BL4CT battery, Standard capacity Lithium-Ion battery is the factory original battery designed & built specifically for the Nokia 5310 cell phone models.Nokia BL-4CT/ BL4CT Li-Ion Standard battery provides your Nokia 5310 cell phone with the standard battery capacity that originally shipped with most Nokia 5310 cell phone models, for very good talk time. This memory free, standard capacity battery, is the factory original, Nokia 5310 Li-Ion battery, rated at 860 mAh capacity.Nokia BL-4CT/ BL4CT battery is compatible with Nokia 5310 cell phone models only. You Never need to condition your battery after the first 2-3 cycles! Charge the initial 24-hour battery charge with the cell phone turned off. Note that a new lithium ion battery"s full performance is only achieved after 2-3 complete charge and discharge cycles. Factory original warranty of One year applies.