Every so often a product comes along that fits the bill when it comes to great marketing gifts you can use to promote your company. Power Banks are one such product and one I have used at Redbows several times. They make great gifts for clients and even giveaways at trade shows and conferences. We all know that you charge them and carry one around so that you can boost the charge on your mobile phone or tablet but how do they work and how do you choose the right one for your promotion?