High-performance Afocal lenses quickly convert the night vision monoculars or goggles into a long-range night vision devices. The SPI afocal lenses incorporate very fast optics and perfect field of view. Ideal for long range observation. Afocal lens by SPI is simple and quick to install in front of existing front lens of night vision device for instant visual enhancement. To mount the afocal lens to the device, screw it into the threading of the standard 1X objective lens.