Light State DIN# 3 / Dark State DIN# 11Unit 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 MillisecondsDark To Light Delay: 0.2 SecondsSolar Powered with Rechargable Backup BatteryMinimum Lifetime of 5,000 Welding Hours