information to and from each other in a wireless mode when more than one bolt detector 26 u2032 and more than one mobile transmitter receiver 40 are used all thickness detector assemblies can be interrogated in sequence or at different time intervals or under different frequencies or by other unique identification codes in use the interrogation of a single thickness detector assembly 26 u2032 40 is initiated by the computer 50 a first signal is sent to the mobile transmitter receiver 40 which in turn sends signals to all wire loops 36 the mobile transmitter receiver 40 reads the condition of each loop 36 and sends this information to the base transmitter receiver 44 in a wireless mode the base transmitter receiver 44 relays this information to the computer 50 wherein the information is interpreted and displayed on the computer screen as an indication of the actual thickness of a wear plate 24 inside the mill when the thickness of the wear plate reaches a specific measurement the mill can be scheduled for preventive maintenance and replacement of all the wear plates inside the mill the mobile transmitter receiver 40 and the base transmitted receiver 44 are explained herein by their functions rather than by their specific structure the structure of these devices is known to those skilled in the art of communication devices and therefore.