Auto Dimming Welding Helmets eliminate bothersome face shield flipping. Now you can see exactly where you are at all times and concentrate on the work. A photocell senses the light from the arc and dims the liquid crystal lens in a blazingly quick 0.025 milliseconds. It lightens just as quickly when you stop. Model 19013 has a view area of 1.16in. x 3.75in. and a fixed #11 lens, just right for Mig welding. Shut off is automatic after 30 minutes of idle time. Helmet uses two AAA batteries (included) and features a low battery warning light.