Trade name: Gs Natural-Knee Flex Systems. Technical Name: Implantable Material. ANVISA registration number: 80199020013. Risk class: III. Affected model: NKII and Gender. Serial numbers affected :. 61837057, 62020365,62046213,62054637,62054638,62094875,11004878,11007656,11007719,62098206,62107229,62125578,621773770,62178184,62188142,62190389,62192798,62194526,62196210