Aluminum jig uses two rollers to guide your stone evenly over the sear to let you get the exact angle for a crisp, clean trigger pull. Three modes allow you to pre-set, mate, and set up for secondary stoning to ensure that the hammer-sear engagement is precisely set. An adjustable angle mode is also available for experimenting with different angles. Brass rollers prevent over-stoning the sear and an adjustable insert and knob work with the sear block to lock the sear in place to prevent movement. SPECS: Aluminum block, brass rollers. Includes instructions.