The outside adjuster allows the user to variate the shades from DIN 9 to DIN 13. This helmet has a special turnover headband mechanism that makes welding for long periods of time more comfortable while reducing fatigue so you can weld even longer. This solar powered helmet uses high performance solar cells for regular operation with 2 built-in 3V lithium batteries as power back-up. Complies with DIN, ISO, EN safety standards as well as ANSI Z87.1-2003 standards. Lenses: Titan Tools Part# 41264 Headgear: Titan Tools Part # 41263 Automatically changes from a light to dark state in 1/30,000th of a second when arc is struck Outside sensitivity adjustments provide clear vision both prior to and during welding Variable shades from DIN 9 to DIN 13 Special turnover headband mechanism allows for greater comfort and reduces fatigue Durable, light weight material is corrosion resistant and flame retardant.