ASTRO Gaming A40 TR  Gaming Headset for PC, Mac- White Superior Fit & Finish: premium materials and construction, highly adjustable and lightweight Mod Kit Ready: go from an open-back to a closed-back noise isolating headset with swappable Mod Kit components (sold separately) Nominal impedance: 48 ohms. Customizable Speaker Tags: personalize your headset with our magnetic speaker tag system.Frequency Response 20 - 24,000 Hz Swappable Precision Microphone: Highly sensitive Omni-directional mic that focuses on your voice and minimizes background noise. It can be positioned on either side of the A40 TR headset.