The Forster Accu-Ring Die Lock Ring is a precision reloading tool that provides reference marks in increments of thousandths of an inch (0.001") for accurate die adjustments.Forster Accu-Ring Die Lock RingPrecision reference marks in 0.001" incrementsPrimary use: Sizing dies for precise headspace length controlSecondary use: Fine adjustments to bullet seating depthsCompatible with sizing and seater diesEssential for serious reloaders who demand precision and repeatability in their cartridge preparation allowing you to zero in on exact specifications for consistent ammunition quality.