The Boonton 42A RF Microwattmeter provides for 10 nW to 10 mW (7 ranges); Full Scale dBm Ranges of -50, -40, -30, -20, -10, 0 & +10; Solid State, Programmable Instrument; For use with the 41-4A (200kHz to 7GHz), 41-4B (200kHz to 12.4GHz) or 41-4C (200kHz to 1GHz) Power Heads.