K2 KII EMF Meter & PSB7 (SB7) Spirit Box EVP Device K2 EMF Meter Deluxe w/built in constant on/off switch Detects ELF range (50 to 1,000 Hz) & VLF range (1,000 to 20,000 Hz) P-SB7 Rev 04 comes w a round external speaker that attaches with a cord or a spout. Black or Blue speaker. The P-SB7 utilizes a milli-second adjustable Forward or Reverse frequency "sweep" technique FM frequency sweep frequencies from 87.5 MHz to 108 MHz.