Redding Neck Bushings are available in various diameters and made for use with RCBS Gold Medal Match series dies. Because of variances in thickness for the neck brass the standard die sizes the neck under the preferred diameter. To get the proper tension on the bullet an expander ball is pulled. In addition these bushings are self-centering and changeable which makes it possible to set the amount of tension on a bullet with precision. As a result there is less work on the brass helping prolong life while increasing accuracy.