designer's own words:VACUO was designed to take advantage of the LEDs special features of long life and high lumen output per watt to create a versatile lamp both waterproof and light. It can be used indoors and outside. VACUO lights use 6 LEDs supplied by two lithium ion batteries that are recharged by 8 small solar cells. Because the lamp has its own power supply it can be vacuum sealed. The VACUO relies upon the clean funtional elegance of its components for its visual aesthetic.