ASTRO A40 TR Headsets arrive setup for open back performance. From a user perspective, this means they create less ear fatigue and can be used for long gaming sessions, but they allow some sound to move freely in and out of the speaker enclosure.
With the addition of an ASTRO Mod Kit, the A40 TR Headset can transform into a closed back headset. From a user perspective, they let far less sound to move in and out of the enclosure, effectively creating improved noise isolation.
For more info visit – How To Geek: Open-back and closed-back headphones.