USA seller 4-1/4" X 2" Auto Darkening Welding Helmet Mask Hood Lens Filter 3/12 auto darkening sloar welding helmet filter Light State DIN# 3 / Dark State DIN# 12 Unit size: 4-1/4" x 2" (108 x 50.8mm) Viewing area: 3-6/7" x 1-1/3" (98 x 35mm) Switching Time: 0.5 Milliseconds