Probyn-Williams one-hand face mask grip (1901) with fingers 4 and 5 on the chin generating a chin lift/head extension. There is no strap holder on the dome. Reprinted with permission from Probyn-Williams RJ: A practical guide to the administration of anaesthetics. London, New York, and Bombay, Longmans, Green and Co., 1901, pp 73.⁸⁶