When I bought the F3 it came with a just the high speed vertical head. While this has been very useful so far, its speed range of 1000-6000 rpm suggests that it is best suited to small cutters and probably not the right thing to use for milling large pockets or hard materials (1000 rpm is just about ok for an 8mm carbide end mill in steel). My searching for a vertical head was finally rewarded (even though it’s not the correct colour or shape for my model):

As with the high speed head, this can be rotated a fair way either side of vertical. It has a taper pin for locating it at the vertical position, just visible below the left clamping bolt. The taper pins have a most civilised arrangement for extraction, with a nut on a threaded portion of the pin being tightened against the casting to pop the pin out. 

This should be the last of the big accessories that I’m seeking for the F3, now that I have the horizontal overarm, the slotting head and the high speed head. Now I just need a sensible place to store them all.