RCBS Tungsten Coated Neck Sizing Bushings provide the right tension on bullets without needing traditional case lube, thanks to their Tungsten Disulfide coating.
These bushings are self-centering and should only be used with RCBS Gold Medal neck sizing dies, with recommended sizes above and below the target diameter.
To choose the correct bushing size, measure the loaded cartridge's outside neck diameter and subtract .002"-.003", or calculate by using the case's neck wall thickness, bullet diameter, and the same subtraction.