Thanko’s Solar-Powered Cap Fan...

This cap with an embedded solar-powered fan might not be totally

all-weather, but it comes pretty close. It protects your mug from the

harmful UV rays of the run while making good use of all that solar

energy to power up the fan at the top of the cap.

The cap-slash-fan is available from Thanko Japan for ¥1,260 (~$16 USD).