Timetec: You power, our pride! Battery Features: - Built-in overcharge protection - Grade A Cells. Certificate: CE & RoHS - Safe: Built-in overcharge protection - Tested with strict quality control standards - All Timetec batteries are produced through strict procedure that meet the ISO 9001:2000 standard Charger Features The charger automatically detects polarity, and stops charging when the battery is full. (Indicator: Red = charging, Blue = fully charged) Multi-connectors (folding plug and USB port) allow you to charge two batteries simultaneously Video instruction in English & Español available in YouTube: search "Timetec Universal Charger". Compatible model Galaxy S4 S IV SIV, I9500 SCH-I545(Verizon)SGH-I337(AT&T) SPH-L720(Sprint) Note:Can Not Fully(90-95%) Charge Samsung S4 as the output voltage is lower(4.2V) than the 4.35V S4 require Using Tips: 1. To reach the best performance, please full charge and discharge your new battery for 4 to 5 times. 2. Keep the battery power between 5%-95%. 3. Avoid overcharge and over discharge. Please stop charging when the battery is 100% charged 4. Please do not charge the battery over 24 hours, overcharging may shorten its lifetime. Unplug the charger after use. 5. Re-charge the battery once every three months when it is not in use 6. Do not use the product in high temperatures. Use Timetec Xamp External Battery Back-Up just in case! Search ASIN: B008TY621A