The Smarter Tools ST-1S auto-darkening welding helmet is designed to protect the eyes and face from specks, spatter, and harmful radiation under normal welding conditions. The Auto-darkening filter automatically changes from a light state to a dark state in only 1/25000S when an arc is struck and it returns to the light state when welding stops. The adjustable sensitivity and response time makes this helmet the smart choice among other welding helmets.