2X ProdiCell Premium Battery + Travel Charger for the Samsung Galaxy S 4G [Experience Extended Battery Life] ProdiCell premium batteries are only authorized to be sold by QuickShippers/ProdiCell. It is illegal to use our trademarked product logo without our express permission. Unauthorized sellers will be reported. Tested to be comparable to the OEM battery! No extended battery door is required. Battery generally improves after 4-5 charge cycles. Please allow the battery to fully charge and discharge 5 times to enjoy max charge potential. We pay extra for high-quality lithium-ion cells! FREE 3 month warranty! If your battery dies within the first 3 months from purchase, we will replace it for free.