4-1/4" x 2" Auto Darkening Welding Lens Filter 3/11 Light State DIN# 3 / Dark State DIN# 11 Unit size 4-1/4" x 2" Viewing area 3-5/6" x 1-1/3" Switching Time: &lt;1/2000 Second at Room Temperature Solar Powered ~ Minimum Lifetime of 5,000 Welding Hours