250 mm Gel fuel. For use in your existing  Wilesco or Mamod  solid fuel tray. This Gel fuel unlike the tablets  does not contain Hexamine or any other regulated substance and is a great alternative to solid fuel tablets.   It is non hazardous and can be transported and stored safely in any temperature for any length of time. It burns leaving a  fine white ash and gives a good run time  in your engine . 250mm suitable for about 10-12 runs in an  average size engine.