... with USB port and SD card reader,use Lithium-electricity rechargeable battery.can wear it,belt it&waistband, easy to ... gymnastics demonstrations, outdoor activities, hiking guide, street selling, the square provisional assembly, speech activities, the exhibition guide, such as shopping ... :7.2~9V Built-in with Two 3.7V2400MA Lithium-electricity rechageable batteries Charging time:6~8 hours Operetion ...