Two London designers, Martin Riddiford and Jim Reeves, have developed a light that requires no electricity or batteries and works by using gravity. The light can be mass produced for less than five dollars and will be given to people in developing countries.

The light works by filling a bag that hangs from it with rocks or sand and as the weight slowly descends a generator powers an LED light for up to 30 minutes. The bag can then be lifted back up and run again.

The pair started an Indiegogo campaign to help fund the manufacture of the device and with 20 days still left have already surpassed their target funding by almost 500%.They will distribute the first 1000 lights for free in Africa and India, where many people have no access to a power grid, and get feedback on how well they work in order to produce their next version called the MK2.