The Mackie HR624 is a THX-approved, six-inch, two-way active reference monitor. The HR624 is designed to work perfectly with the Mackie HRS120, 12" 400-watt active subwoofer system as well as the Mackie HR824 active 8" monitor in surround installations. The Mackie HR624 is the ideal choice for smaller recording studios, or home and project studios looking for a monitor with the best combination of features and value. Its six-inch woofer offers smooth, detailed mid-range frequency responsiveness . With extremely even dispersion for a wider "sweet spot" and user-adjustable controls for different acoustic spaces, the HR624 is an excellent choice for high precision, near-field sound reinforcement. What's more, given the HR624's high output, wide frequency response and small size, it is also ideally suited for rear surround sound channels in home theater installations. Mackie is so confident in the HR624's frequency response that each speaker comes with a certificate of calibration.