There are three stl's.
A complete one and the same model split roughly in half.
The complete one needs a support structure wheras the split one doesn't however you may have issues joining the two halves, I had to fill in the gaps with a filler before painting.
If the half models warp a little so the flat sides do not touch I have found a little trick to help (probably only works with pla).
Put the halves together and wrap an elastic band tightly round each end.
Dip one end in hot water, enough to soften the plastic.
the elastic should bring the two halves in contact but you can help by gently squeezing them together.
Repeat for the other end.