1.Intelligent circuit of power recharging inside. 2.Good quality of solar recharging, even in weak light condition. 3.Use lithium battery. Long use-life. 4.Use the 64 bits IB button. High security. 5.Solid brass handle and solid brass cover. European style. 6.Easy to operate and responds very quickly. Product Specification: 1. Supply Voltage： DC 3.6V （500mAH Li-ion battery） 2. Standby Current : <3uA 3. Operating Current: 200 mA 4. Operating Temperature： -20??0? 5. Li-ion battery use_life: more than 5 years