The Lee case length gauge is a precise and easy way to trim brass cases to length and square the case mouth. Requires a Lee cutter and lock stud to function. The first step to successfully trimming brass cases with the Lee case length gauge and shellholder is to take the Lee lock stud (sold separately) and screw it into the shell holder. Next the length gauge needs to be screwed into the case trimmer cutter (sold separately). the length gauge is set to cut each case within specifications. After the tools are screwed together the next step is case trimming. Just put the empty brass into the shellholder, insert the case length gauge into the empty piece of brass and turn the cutter until the piece of brass is trimmed to the predetermined length. It is that easy to get consistent case lengths and square case mouths helping to keep reloaded ammunition as accurate as possible. Specifications: - cartridge: .458 Winchester Magnum - material: steel