Hyperion Samsung Galaxy Express 4G 3500mAh Extended Battery + Back Cover (Compatible with AT&T Samsung Galaxy Express 4G SGH-i437) Extend your talk time on your Samsung Galaxy Express 4G SGH-i437. 3500 mAh Battery Capacity (with Extended Back Cover). Batteries use Hyperion Accessories "A" Grade Lithium Ion Cells. Designed by Hyperion Electronics Accessories. Shipping Same Or Next Business Day. 12 Month Product Replacement Warranty.