I hope this question hasn't been asked. I looked, couldn't find it, and must get ready for work now. Anyways, the question I have is: Is it possible to buy a Blinder M20 and then later buy the other two heads making it an M40 or does the M20 only have plugin slots for two heads? I currently don't have the money for either, but I don't want to wait forever to get the M40 when I can get the M20 much sooner and at least have front protection from the LEOs here in Irving. Thanks in advance.