Wisdom Wise Lite 2 Cordless Hard Hat Mine Light, MSHA Certified These lights are light weight (less than .5lb), waterproof to 20+ meters (IP68 Certified), and unlike most lamps on the market, these lights were designed for underground mine use so they are seriously rugged and will last for years! These lamps have two modes of operation as follows: High / 8,500 lux / 167 lumen / 16 hours of operation Low / 1,800 lux / 50 lumen / 60 hours of operation