The invention relates to a component for holding down measuring leads and measuring devices in a groove (6), provided therefor and having holes (7), of a machine part (5). It is characterized in that the component is designed in the form of a disk (1) which has a cutting edge (3) on its circumference, the cutting edge (3) not being formed continuously over the entire circumference but consisting of two partial cutting edges (3', 3'') circumferentially opposite one another. In addition, the disk (1) has a central opening (2) in the form of a hexagon socket. For fitting, the disk (1) is put into the hole (7) in such a way that its two partial cutting edges (3', 3'') point in the longitudinal direction of the groove (6), then a hexagon socket key is inserted into the opening (2) of the disk (1) and the key is turned while the disk (1) is pressed down at the same time, so that the cutting edges (3', 3'') cut into the material of the machine part (5) and jam tight.