... 1 second SPECIFICATIONMeasuring Principle:Keypad:Transit time difference18 Key with tactile actionPipe Size:Response Time:S Type : 15 mm ~ 100 mm ... (1/2" ~ 4")Less than 1 secondM Type : 50 mm ... totalizer,Million Gallon, Cubic Feet, US Barrels,time, dateImperial Barrels, Oil BarrelOutput:Time UnitPulse (Open collector)Second, Minute, Hour, ...