Best alternative to primary battery, standby time and call time are equal. 2. Lithium-ion batteries provide excellent continuous power supply for your equipment 3. Good quality and long service life 4. Compared with nickel-cadmium batteries, lithium-ion batteries have no memory effect. 5. If you do not use batteries for a long time, please keep them in a cool and dry place and charge them every three months. capacity 4000mAh