The Model 840-C is a powerful handheld dual-microprocessor based optical power measuring instrument. It makes sensitive DC or AC Peak-to-Peak optical power measurements with the convenience of full spectrum sensor calibration, quick sensor change, and a host of user-friendly features. Accurate and reliable fiber optic power meters for the test and measurement of. EC DECLARATION OF CONFORMITY Active Isolation Module Set Series Model 840-C We declare that the accompanying product, identified with the " " mark, meets the intent of the Electromagnetic Compatability Directive, 89/336/EEC and Low Voltage Directive 73/23/EEC.