We are currently working on that. It should be available in a few months. It is located in the middle of the page, in the table. Many people use small rocks, paintballs or any small object can be used as a projectile. That would be the WR-4 .
Paintballs are temperature sensitive.
The smaller they are, the harder it will be for them to break. This will soften them up a bit. You can also hold them in the palm of your hand and close your hand over the paintballs. This will give them some heat also. It is important to keep them out of the heat, cold, and the sun.