The Night Optics USA proprietary (patent pending) Day/Night Adapter quickly transforms a daytime riflescope into a 24-hour system by allowing quick connection of a PVS-14 night vision monocular to the eyepiece of the daytime optics. A unique adapter mechanism ensures the Day/Night Adapter can be attached to, or detached from, virtually any daytime scope in the field without tools. The Adapter provides an easy and secure alignment of the two systems while allowing the night vision device to swing to an alternate locked position on the side of the weapon. Configuring a riflescope for either day or night firing without loss of weapon zero is now as simple as pressing a button.