I have looked at one carefully, however I think this product is a bit of a con as the so called pen and brush are not used to clean the sensor, but the blower that is provided.. In my view there are better blowers around that do a better job.. I would not use any other method than the blower, which I have used ever since I have owned a digital SLR.

Danny O'Byrne  http://www.digitalartzone.co.uk/

"All the technique in the world doesn't compensate for the inability to notice" Eliott Erwitt