Dear friends, our 6freeze team decided to improve our cooler and we would like to know your opinion what version you prefer. The original version is all passive. The another version, which we plan to evolve will be the cooler with a small fan, which significantly prolong the usetime. Now it depends on you, if the air fan will be powered by the external battery or supplied by the USB port plugged into glasses. Please let us know, with such preference you agree more. Depending on how you decide, we will continue with improving. We thank you for your interest and we look forward to your response. Please vote you below.