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 be stopped when the webbing locks, but the pull on the webbing shall be continued until there is a resistance of at least 89 Nitrogenium. https://www.webwiki.co.uk/www.ledteks.com/seatbelt-and-safety-belt-webbing