"The 4308 is a wattmeter from Bird. A Wattmeter is an instrument for measuring the electric power (or the supply rate of electrical energy) in watts of any given circuit. Electromagnetic wattmeters are used for measurement of utility frequency and audio frequency power; other types are required for radio frequency measurements."," Additional Features: ","Designed specifically for the two-way and cellular service. 440-960 MHz, 1.5-50W, Portable Wattmeter, no elements to purchase as this meter comes with the only element that is needed. General purpose field power measurement from 440 MHz to .96 GHz and up to 50 watts. Uses a single permanent broadband element with a 4-position range switch, 1.5W, 5W, 15W, 50W. Same rugged metal housing as the Model 43. Quick Change (QC) connectors to minimize the need for adapters when making critical measurements. Optional pelican case has storage for 50W Bird RF Load and connector\/adapters."