The Type 4189-L-001 is designed for high-precision free field measurements where a high sensitivity microphone is required. Precision sound measurementPremium Class Sound Level MetersEquipment in accordance with IEC 61672 class 1 Microphone: Type 4189Preamplifier:  Type 2669-LThe unit is assembled in a clean and sealed room environment, after which a unique type number and a unique serial number are assigned. This means that the combined unit has better accuracy and long term stability and is treated as a complete unit.The drive also contains TEDS, which means that the serial number, type, and sensitivity information is stored in it. Better stability and accuracy. Because the unit is mounted in clean room facilities, there is no contamination.Easy to use. Your front-end analyzer and software will automatically detect the type number, serial number and sensitivity because of the built-in TEDS technology. There is no need to manually enter this for all channels.Calibration integration. T EDS technology means that the microphone is automatically detected and identified by its data acquisition software, allowing it to be easily integrated into its calibration database.Less errors. Because your data acquisition software automatically knows the microphone type, serial number, and sensitivity, manual inputs are greatly reduced reducing human error.