The M2124 is a rugged, clip-on night vision device (CNVD) based on military nomenclature AN/PVS-24 used by U.S. Special Operations Forces. The advanced design of the Model 2124 eliminates the typical requirement of removing a primary/day sighting system, since it mounts in line with a standard day optical sight. Combining day and night vision sights reduces the need to re-zero, since the primary sight remains undisturbed. Using the M2124 with a primary sighting system also maintains a user’s consistent eye relief and shooting position and retains the user’s muscle memory.