What is the difference between a half-zip and quarter-zip anorak?

A half-zip extends from the collar to roughly mid-chest, providing more ventilation at the neck and easier overhead entry. A quarter-zip extends only a few inches below the collar, offering a cleaner look but less ventilation and a tighter neck opening. For most riders, the half-zip is more practical because it provides better airflow and easier on-off. Quarter-zips are chosen primarily for aesthetic reasons.