Forster Neck Tension Gage 308 Red. Each NTG provides reloaders with the information needed to create exacting neck tensions during the bullet seating operation. Use after case neck sizing and before bullet seating to help determine optimal inside neck diameter for consistent release of a bullet from your reloaded rounds. Allows for inspection of the inside diameters of case necks to be sure a donutin has not formed at the neck-shoulder junction. This kit includes all five calibers available. Each Neck Tension Gage (NTG) Inspection Tool consists of four stepped diameters that increase in size until reaching the handle. Each diameter is etched on the metal tool. Simply insert the stepped end of the tool into the neck of your sized case sliding it in until one of the diameters achieves a slip fit in the case neck. Use the resulting value to fine-tune your case preparation. Specifications for Forster Neck Tension Gage: Manufacturer: Forster Weight: 0.105 lb Color: Red Fabric/Material: Metal Features of Forster Neck Tension Gage Quick Accurat Affordable way to check one of the most important factors for quality reloaded ammunition 4 steps ground in .001in increments to +/- .0001in tolerance Package Contents: Forster Neck Tension Gage Forster NTG-308: Neck Tension Gage 308 Red