Thermal clip-ons are recognized as one of the most universal systems on the market. Imagine when you are hunting during the day, you're out in the field, night time falls and you only have a dedicated night vision scope. What do you do? You have to remove the daytime scope and place the night vision/thermal scope on the rail. What is the downfall? The downfall is that when you put the daytime scope back on the rail you will need to resight the scope each and every time you take it off. The solution is instead of purchasing a dedicated night vision and or thermal scope, you purchase a thermal and/or night vision clip-on. A clip-on is a system that essentially mounts in front of a daytime scope without the need to resight the daytime scope to work in conjunction with a clip-on. The clip-on is available in three resolutions- 256, 384 and a 640 resolution. Clip-on systems work with daytime scopes that have a minimum of a 24mm objective and works all the way with a 56mm objective scope. Some of the daytime scopes that work best with a clip-on are Night Force, Trijicon, Swarovski, Vortex, Khales, Leupold, Steiner and many more. Once the thermal clip-on is mounted in the front of the daytime scope you will be able to see heat signatures through the daytime scope. You will have the ability to be able to use the existing reticle from the daytime scope for target acquisition. The major players in the industry are AGM, Pulsar, ATN, Infiray and many more.