Meet the Caveman Flare Mini: a gun barrel temperature sensor that helps improve the safety and accuracy of your weapon. It fits barrels from 0.675″ to 2″ in diameter and can handle temperatures up to 450F degrees. It lets you know when your barrel is too hot to touch by going from dark to a bright color.
The Flare Mini lets you know when your barrel is getting hot enough to cause bullet drift. You can find out more about it here.