The Reference Calibration kit is recommended for highest quality speaker measurements and is used for setting up HDP-Express, HDP-3 units.

It includes:
• DEQX measurement, analysis and correction software for PC
• 5 meter USB cable to connect DEQX processor to PC
• DEQX Calibrated™ Earthworks M30 measurement microphone
• 5 meter balanced XLR microphone cable

A boom microphone stand (not supplied) is required for speaker and room measurements.
Stands are typically available for under $100 from a local musical instrument supply shop.