The 
  270 piece set contains 90 steel balls and 180 interconnecting rods. The rods 
  are a selection of red, green, 
  blue and yellow.
 
  Each Geomag set comprises: 
  
    - Spheres - made from nickel-plated steel and 12.7mm in 
      diameter.
    -  Plastic bars - 27mm long and 7.4mm in diameter, comprising 
      of two magnets at each end connected by a steel pin.