A P4 fan and heat sink from the cpu. The fan has it's own shroud and I am gonna figure a way to mount the heat sink on the top of the head cover for even more air cooling. The fan is .o4 watts and.68 amps. It measures 4"x4" and is 12v dc.
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you can run it/test it on a 9 volt battery if ya want, but that won't push it very hard. the heat sink is 3.5"x 3.5".