Rules on high school discus ring construction have changed over the years to minimize risk to athletes and spectators, though the size of the throwing ring itself has not been altered. These changes include requiring cages over the rings, and reducing the allowed throwing sector. Rules for the ring and throwing sector are the same in high school and college, though college rules are stricter on size for discus cages and slope percentage.
A high school discus ring has a diameter of 2.5 m, which translates to 8 feet and 2.5 inches. This is larger than a shot-put ring, which is 7 feet in diameter. The circle on high school discus rings must either have a plastic or metal band that rises 3/4 of an inch over the circle’s level, or a 2-inch-wide painted line.
The throwing sector size for the discus ring is 34.92 degrees. Prior to 2006, the National Federation of State High School Associations allowed the throwing sector to measure up to 40 degrees. Tighter sectors require athletes to have more control during their throws. The throwing sector is marked on the ground with the measurement taken from the center of the throwing circle.
Starting in 1993, the National Federation of High Schools required that discus rings have a fenced discus cage positioned over them. Typical fences are 10 to 14 feet tall, with a maximum front opening of 24 feet. In college, the fence must be a minimum of 13.12 feet high, and the front opening 26.8 feet wide.
The percentage of slope from the throwing sector can be no more than 1 percent. College rules are stricter, allowing only 0.1 percent slope.