The solenoid is rated for 5v but the stock board pumps 7 into it. Aftermarket boards go for the full 9v from the battery. Doesn't make much difference so I won't go into the specifics.
As told by Stobaeus ...someone who had begun to learn geometry with Euclid, when he had learnt the first theorem, asked Euclid "What shall I get by learning these things?" Euclid called his slave and said "Give him threepence since he must make gain out of what he learns".
