Here is an F1, followed by F2
The F1 was a 2nd generation semiauto. Came out the same year as the Promaster, Pro/Am, and Automag.
It was the first "light" paintgun. Before the F1, paintguns like the 68-spec, Golden Eagle, and PMI3 were VERY HEAVY- 4-5 pounds.
The F1 was barely 2 pounds, so some people assumed that the light weight meant is was cheap and weak, though that was not the case.