Ebest Black 3200mAh Extra Power Backup Extended Battery Case For Samsung Galaxy SIII S3 i9300 100% brand new 3200mAh External Backup Battery Charger Case for Samsung Galaxy Note i9220 To charge the portable battery, simply plug in the USB contactor into the portable battery The other end contact to either an USB power adaptor or an USB socket of a computer To charge the phone, simply slide the phone into the portable battery and slide ON-OFF switch to on Dimension: 159mm (L) x 86mm (W) x 18mm (T)