Use the screw from the source model or a small (5-8mm) M4.
For some reason, Jerhaad's version showed a terrible seam down the back, no matter how many times I worked with it. Whats also interesting, is the model shows a sold back near the top, near the small hole. Mine shows solid as well, but prints out with a small square hole in the back.
The user re-uploaded this model. The user is not the original author of the model.