As of my last knowledge update in January 2022, I don't have specific information about an "East Power 4V 0.5Ah Rechargeable Battery." However, rechargeable batteries typically share common characteristics. If this is a new or specific product introduced after my last update, you may refer to the manufacturer's documentation or product details for accurate information. 

In general, a rechargeable battery with specifications "4V 0.5Ah" implies:

- Voltage: 4 volts
- Capacity: 0.5 ampere-hours (Ah)
- Rechargeable: Can be recharged multiple times

These batteries are often used in various electronic devices, including small appliances, toys, and portable gadgets. For precise details about the East Power 4V 0.5Ah Rechargeable Battery, please consult the product documentation or the manufacturer's information.