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. GOG offers these inserts in both aluminum and stainless steel both with outstanding internal honing.
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.