The Freak Insert is at the literal core of the Freak barrel system.  Paintballs can change size from thousands of variables; temperature, humidity, elevation, storage conditions and manufacturers to name a few. The interchangeable bore system allows players to adapt to whatever paintball throws at them. 

The boremaster kit gets you 8 of the most common bore sizes and a rugged case to carry them in, the case also holds two freak tips and a back.