The Adrenaline SAS Freak® insert is a result of nearly two years of research and development. Each insert goes through a process of electroless nickel plating while injecting it with a proprietary formula of PTFE (commonly known as Teflon®). The result is a barrel permanently bonded and coated with the second slickest coating on Earth. The benefits of SAS are higher velocity (which means a more efficient platform as you can lower your secondary regulator pressure), increased consistency (enabling you to enter the field closer to 300fps), and increased accuracy due to the downsizing (eliminating gaps around balls that are not perfectly round). We've found that downsizing two or three bore sizes is ideal.The full insert set is based on the Freak® XL body length and comes in the following bore sizes: .678, .680, .682, .684, .686, .688, 690, and .692. Four Adrenaline Barrel Sleeves are included and it also includes the standard rugged Freak® case to carry them in. The case also holds one Freak® tip and one Freak® back. Each insert is lasered by Adrenaline to also show the bore size on the end of the insert so that it can be selected while still in the Adrenaline Barrel Sleeve or the standard case.