The Salt Water Fuel Cell Giant Arachnoid Kit gives children a chance to learn about new forms of clean energy, while building and powering their very own toy - feed it saltwater and watch it scurry away. Building on the success of OWI's award winning Salt Water Fuel Cell Car, this second generation appears to be just as dynamic...maybe a little frightening. After activating the fuel cell module with a saltwater mixture, the magnesium metal sheet (3 sheets included) can operate the Spider for about five to seven continuous hours. To stop, remove the fuel cell module, rinse with water and dry. All kit materials are environmentally safe, and non-toxic.