A semi-space filling set for making a wide range of biochemistry molecular models. Packed in two compartmented moulded plastic boxes. Consists of Spheres : Carbon - 66 Oxygen - 40 Nitrogen - 34 Sulphur - 2 Metal- 2 Phosphorus - 6 Hydrogen - 105; Links : Short White - 100 Non- visible - 60 With instruction leaflet.