Radiation measuring device PCE-MFM 3000 for determining static and alternating magnetic fields. Max-Min memory function, data hold function, and polarity display. The magnetic field tester PCE-MFM 3000 is suitable for measuring both static and changing magnetic fields. Therefore, the magnetic field tester is ideally suited for checking components such as solenoid valves or relays, especially in industrial settings where it is crucial to quickly verify whether a valve is functioning correctly or a relay is still switching. The PCE-MFM 3000 measures the established magnetic field through a housing, eliminating the need to open the device, allowing for quick and accurate functionality checks. The very flat measuring tip enables the external probe of the magnetic field tester to penetrate small openings in a measurement object. This is particularly advantageous when measuring transformers with air coils. The magnetic field tester is also suitable for explaining and demonstrating the behavior of a magnetic field, as the numerical display clearly indicates any increase or decrease in field strength. With its small measuring ranges, this measuring device is well-equipped to safely measure even small magnetic fields. Small holding magnets or magnetic guide rails, which possess relatively weak magnetic fields, can be effectively captured with this device.