Sunvalleytek via Amazon offers the RAVPower Element 10,400mAh External Battery Pack in Black or White, model no. RP-PB07, for $32.99. Coupon code "PB07SD01" cuts it to $25.49. Plus, Prime members bag free shipping. (Non-members can spend $35 or more to bag free shipping; otherwise, shipping adds $5.55.) That's $2 under our mention from two weeks ago (although that included a car charger) and the lowest total price we could find by $10. It features 1-amp and 2.1-amp USB outputs and is compatible with iPhone, iPad, iPod, and many smartphones.