A plug gauge (1) includes a support and protection system that defines a longitudinal axis with a handle (2) closed by a cap (13) that includes electronic devices for the wireless transmission of electrical signals representative of a dimension to be checked, and a probe (6) including a measuring armset coupled with a transducer for generating electrical signals. The probe is connected to the cap of the handle by means of an interface element (8) that includes mechanical references to prevent rotations of the probe with respect to the handle about the longitudinal axis.