Granted, that's not really a fly-fishing accessory, but a wonderful addition. The solar charger in saltwater-resistant lamination has proven to be very useful on my journey in Kamchatka to keep the batteries of my camera alive. In combination with the Powerbank, a mobile additional battery for USB devices, notebooks and any device with 12-24 V charging voltage and the high capacity of 18,000 mAh (67Wh), you are even more flexible.
The Powerbank also uses state-of-the-art components and technologies to maximize efficiency, performance and longevity: high-quality Li-Polymer batteries, MPP converters with up to 97 % efficiency, lowest loss semiconductor devices. The case is made of UV-resistant, robust materials that are grade-matched and therefore recyclable.