1,APPLICABLE SCENARIO: Frequency meter can be used in electronic measuring instruments; Traditional manufacturing areas, metrology laboratory, wireless communication testing and other fields 2,COUNTING FUNCTION: Digital countdown timer recognizes the built in analog count, backward count, and count phases 3,FLEXIBLE AND OPTIONAL: Frequency meter counting speed is optional, optional relay, collector open output, closed memory power supply 4,TIME DELAY OUTPUT: Frequency counter meter supports more than 10 relay types for free selection, and has the function of time delay action relay 5,TECHNICAL PARAMETERS: External sensor counter for 5V, 24V DC voltage, can be set 1.5x magnification, to determine the ratio between the count and display magnification range 0.0001‑9.9999 Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.