a_;2.5 – 5 cm (largest dimension in any direction)
b_;5 - 10 cm (largest dimension in any direction)
c_;10 – 20 cm (largest dimension in any direction)
d_;20 – 30 cm (largest dimension in any direction)
e_;30 – 50 cm (largest dimension in any direction)
f_;>50 cm (largest dimension in any direction)