This model is a spare dart holder for the Nerf Jolt EX-1. It attaches to the top of the gun's barrel. This model is very robust once attached to the gun, and will not move or rotate in any way. Print in black plastic for best color match. UPDATE: Two dart model now available. The two dart model has contrast sights. Read instructions on how to assemble. Two colors of filiment recommended. One Dart Model Print with raft, 10% infil for best results. Line up end with notch above front sight and push onto barrel. Two Dart Model Print with raft, 10% infil for best results. Cut three pieces of 1.75mm contrasting filiment. If you use black, pick white, or any color. These will be inserted into the holes in the sights. (OPTIONAL) If needed, drill holes slightly bigger. Holes are purposely tight in order to hold in filiment. Push filiment into holes. You will need pliers to seat properly. Line up end with notch above front sight and push onto barrel.