Hey everyone,
If anyone needs to calibrate their studio monitors or speakers using REW software, check out the measurement microphone from SonarWorks. This mic is used by a lot of major studios to calibrate their systems, and SonarWorks are selling it for same price as department-store mics. It beats the widely used Behringer measurement mic hands down in flat response. SonarWorks also provides a calibration file for the mic measured in an anechoic chamber.
sonarworks.com/speakers/microphone/
Hope this helps!