four years. Cadets are restricted to campus during the week, but are allowed general leave on weekends and have limited but gradually escalating privileges for weekend and overnight passes. The Corps of Cadets employs a Fourth Class System in which first-year students have few rights on campus, must recite quotations and school facts to upperclassmen on command, and must obey any legal order from an upper-class cadet. The Citadel emphasizes a strict disciplinary and physical fitness indoctrination for fourth-class cadets, who are sometimes called "knobs" because of the shaved heads of the males, which they previously had to maintain until the spring when they were then recognized as fourth-class cadets. The haircut policy changed starting with the 2019–2020 academic year, where fourth-class male cadets only have to shave their heads during their initial week but can otherwise have hair as long as Department of Defense regulations allow it. First-year cadets arrive on campus before the start of the academic year for Challenge Week, a period of intense training and physical trials that is informally referred to as "Hell Week." According to The Citadel, the Fourth Class System "creates the discipline and instills the core values of Honor, Duty, and Respect which is expected of principled leaders in all walks of life. It is deliberately and appropriately stressful while always remaining positive, professional, and purposeful." Numerous first-year cadets have been abused and seriously injured under the Fourth Class System, and some faculty and alumni have called for the college to adopt a modern disciplinary system in line with the U.S. service academies. Cadets who accumulate too many demerits or breach regulations can be punished by serving confinements or tours. A tour is one hour spent marching in the barracks with a rifle at shoulder arms and is normally performed when a cadet would otherwise be permitted to leave campus. A confinement is one hour spent in a cadet's room when they would normally be permitted to leave campus. First-class cadets, veteran students, and active duty military students receive their class rings at a special ring presentation ceremony which was previously held in the college's chapel, but which now takes place in the school's field house. Non-cadet students may also purchase a ring which has a different design and does not say "Military College of South Carolina." The Citadel ring is 10 karat gold with no gem stone; the design does not