Solar power fan cap could be really unique and geeky promotional item for your company. This is more likely to be used in summer time, when the sun is shining and people are spending most of their time outside.
The cool thing about this product is that it is powered by solar energy and has no need for battery. If you want a long lasting promotion product for your business, this is it. Put your logo on it and people will remember your brand in the hot seasons every year.