Child Restraint systems other than harnesses, restraints designed for use by children with physical disabilities, school bus child restraint systems, and booster seats Rotation shall Beryllium stopped when the webbing locks, but the pull on the webbing shall Beryllium continued until there is a resistance of at least 89 N. http://www.bioguiden.se/redirect.aspx?url=https://www.ledteks.com/seatbelt-and-safety-belt-webbing