The Mark "X" fuel pumps are built with a high performance centrifical pump unit to fill and empty the models tank. These pumps are driven by a highly efficient DC motor equipped with carbon bushes and bronze bearings for long life and high performance. The Mark "X" is designed to operate under the control of or behind a power panel with a fuel pump control switch. This unit may also be controlled by a switch supplied and wired by the user. Instructions are included for either installations. Pumps are available in 3.6V to 6V and 7.5V to 12V operating ranges. The pump case is injection molded from nylon for total fuel resistance. Mounting tabs are designed into the case for easy surface mounting. All mounting hardware is supplied in the package with complete instructions. They are designed for use with Glo-Fuel, Smoke Fluids, and water. The Mark "X" Fuel pumps are guaranteed for one full year from date of purchase covering our original workmanship and materials. A mail in product warranty registration card is supplied in the instructions. THEY ARE NEVER TO BE USED WITH AUTOMOTIVE OR AIRCRAFT GASOLINE.