Elektromag

I heard somewhere that it serves several classes of basic item, but I'm not sure. Is this the reason why I can't buy most classes of upgrade for my warbird, or is it something else? If it is, then how much experience and money should I have before giving it up? Advice is appreciated, but mainly I would like to know specifically what items it substitutes for, or what it does. P.S which is better for basic warbird, gamma ray or pulse laser?