Get meticulous accuracy with the most exacting tolerance specifications in the sighting industry. From the very smallest to the largest 12 gauge casing, the GSM Site-Rite precision machined caliber specific sighters deliver unparalleled results every single time.Precision machined brass casing for optimum accuracyCaliber specific factory alignmentHigh output laserUnits include (3) three Alkaline button cell batteries (varies by caliber)