The Wilson Combat Custom Barrel Links are machined from solid 416 stainless steel (SS) to varying heights. The 5-link kit includes one stock equivalent link (0.278"), two oversize links (.283" & .288") and two undersize links (.268" & .273"). Higher or lower links may be used for custom applications to raise or lower the point of lock-up. The barrel links are extremely reliable and are capable of withstand the stress of constant use to keep your pistol functioning.