This bundle on Amazon includes the HTC Vive, the Deluxe Audio Strap, and a $100 Amazon gift card all for $599. The HTC Vive alone is $599 at most retailers, including Best Buy and Amazon. So you're essentially getting the audio strap, which retails for $100 by itself, and the gift card for free.
The HTC Vive is one of the most popular virtual reality systems out there, and VR Heads has a great guide if you've never used one before. The games you play will track the movement of your headset and the controllers you hold, giving you a full body virtual reality experience.
The Deluxe Audio Strap is designed to give you 360-degree realistic sound while still being comfortable and convenient. You'll even be able to adjust the padding with a dial to get it just right.
