Unlike dedicated thermal imaging scopes, the thermal clip on systems are designed to be mounted in front and in-line of the day time scope.  The thermal imaging capability of the of thermal clip on system  allows for long wave infrared observation and target identification under adverse conditions including light rain, smoke, light snow, and low light to total darkness.  TI clip on mounts in seconds and requires no re zeroing and allows for use of same day time scope reticle and does not change shooters position to the rifle. This gives operators extreme nighttime capability especially when paired with head-mounted night vision goggles. The thermal imaging clip-on attachments developed on 640x512 sensor are typically long range magnified optics.  It is optimized to provide the best image when paired with 1x-8x magnification, but can be used with scopes up to 12-14x without much loss of image fidelity.  This high resolution sensor provides incredibly crisp detail and shading for rich images and easier target identification.