They were to be German nationals who could prove their Aryan ancestry back to 1800, unmarried, and without a criminal record. Recruits had to be between the ages of 17 and 23, at least 1.74 metres (5 ft 9 in) tall (1.78 metres (5 ft 10 in) for the Leibstandarte). Recruits were required to have perfect teeth and eyesight and provide a medical certificate.[7] By 1938, the height restrictions were relaxed, up to six dental fillings were permitted, and eyeglasses for astigmatism and mild vision correction were allowed.[8] Once World War II commenced in Europe, the physical requirements were no longer strictly enforced.[8] Following the campaign in the West in 1940, Hitler authorized the enlistment of "people perceived to be of related stock", as Himmler put it, to expand the ranks.[9] A number of Danes, Dutch, Norwegians, Swedes and Finns volunteered to serve in the Waffen-SS under the command of German officers.[10][11] Non-Germanic units were not considered to be part of the SS directly, which still maintained its strict racial criteria; instead they were considered to be foreign nationals serving under the command of the SS.[12]