The material consists of a series of ten rods with a constant square section (3 x 3 cm) and variable lengths, from 10 to 100 cm with an increase of 10 cm in length for each rod. For each rod, the first section of length equal to 10 cm is painted in blue (as for the length rods), while the second in red; the red and blue colors are then alternated as the length increases, every 10 cm.
Manufacturer: Montessori BF (Trento, Italy)