Mobile Action Command or MAC is one of the most underrated action figure lines of the 1970's.
The concept is centered on the nameless men of MAC, an international rescue operation similiar to the Thunderbirds, each man has his own quasi futuristic vehicle. The combination of a 2" figure and attractively priced vehicle lured me many times and the lack of a back story intrigued me and millions of other children world wide. The thing I hear most about MAC these days from collectors is "I had that but never knew what they were called!"
Check out the 1977 MAC Catalog on Plaidstallions
If you'd like to know even more about MAC, check out Mobile Action Command Headquarters which has more information and catalogs from other years.