Jump boots (also known as paratrooper boots) are a type of combat boot typically associate with soldiers (called paratroopers) assigned to parachute units. Jump boots are fully laced from the instep to the top and give more support to the ankle whereas ordinary combat boots during World War II were laced just above the ankle and had to be worn with leggings or puttees to prevent mud and dirt from entering the shoe. Jump boots were originally designed by William P. Yarborough for use in the 501st Parachute Test Battalion. Although in modern times, nearly all combat boots are fully laced, modern jump boots are mainly worn as dress and parade boots. They are generally made of smooth leather with toe-caps and heel counters that accept a high polish or "spit-shine". They often have side zips for easy removal. Certain US Army soldiers, notably those assigned to an Airborne unit, are authorized to wear jump boots with their Class A uniforms.