47mm or thousandths of an inch e. g. 046". The difference among a detailed facing and an open one may be an issue of 0. 009" or 0. 15mm. Most people can't see those ameliorations they are measured with some variety of instrument, typically a especially made taper gauge of a few kind or a dial gauge. In addition to the end establishing, other dimensions of the facing also measured with micro able tools contribute to its resistance: the contour of the curve between the purpose where the reed contacts the table and the mouthpiece tip and the true length from the end to the point where the mouthpiece contacts the table are essentially the most crucial ones. In general, the longer the curve, the fewer resistant it is. In average the closer the end beginning, the less resistant it is.