Before revision: A multitude of athletic helmets, including football helmets, batting helmets, hockey helmets, cricket helmets, bicycle helmets, motorcycle helmets and racing helmets, were also developed in the 20th century.
After revision: ski helmets,A multitude of athletic helmets, including football helmets, batting helmets, hockey helmets, cricket helmets, bicycle helmets, motorcycle helmets and racing helmets, were also developed in the 20th century.