I don't think this is a mosfet, it is just a timer, the wiring for a mosfet is completely different.

On second inspection - and much more detail on the original makers site:

http://www.aegwizard.com - found it in my bookmarks

Q: All the MOSFET switch products have 3 wires, how come yours have only 2 wires in and 2 wires out? Does it have active braking?

A: This product does not require you to modify the trigger switch and allow you to connect it in-line with the battery and motor connectors connection. It has active braking feature and all the good stuffs from using a MOSFET. The maximum voltage is 16VDC and 80Amp. The product utilizes different approach to extend the life of the trigger switch and therefore you don't need 3 wires to run a MOSFET and you don't need to deal with the hassle of doing modification to your AEG and void the warranty of your gun!

These still look like a very nice bit of kit though http://www.awsairsoft.com/

James mate, your either a comment whore or completely mis-read what I posted!

It IS a mosfet (of sorts) but instead of using 3 wires it uses the switch contacts as normal.

When the switch makes first contact, however, the current is very low (as a normal mosfet) but as soon as it senses the circuit has been made it boosts the current right up (through the switch contacts).

You follow?