Patuoxun via Amazon offers the Mpow 12,000mAh External USB Battery Pack in Silver for $40.99. Coupon code "MPOW22WT" drops it to $30.99. With free shipping, that's $2 under last month's mention and the lowest total price we could find by $16. It features dual USB ports and a 10.2-oz. weight, which is less than most similar devices.