In general :
Pure Bristle brushes: For fine to normal hair, fine long hair.
The models: Large Extra, Small Extra, Handy Bristle and Pocket Bristle.
The Sensitive models are for very fine or thinning hair.
The Child’s model for children aged between 3 and 6 years.
Bristle & Nylon Mixture brushes: For normal and short thick hair.
The models: Popular, Junior, Handy Bristle & Nylon and Pocket Bristle & Nylon.
All Nylon brushes: For very thick hair.
The models: Universal, Handy Nylon (Detangler) and Pocket Nylon.
Long Hair:
In general, the longer the hair the bigger the brush required. However, if a person is more comfortable with a smaller brush, it may be necessary to use a smaller mixture model instead of a larger pure bristle one.