Highlights: Ultra slim design: the thickness is only 1.3cm! Power switch Enhance phone signal Protect your iPhone from scratch Power check indicator on the back Charged by PC/laptop's USB (Universal Serial Bus) port Compatible with iPhone 4 Specification: Weight: 65g Capacity: 1900m Ah Cell type: Li-Polymer battery Dimension: 125x 63x 13mm Output voltage: 5 V Output current: 500m A Standby time: up to 230 hours Talk time: up to 6 hours Internet use: up to 5.5 hours for 3G network or 8 hours for Wi-Fi network Audio playback: up to 30 hours Video playback: up to 8