This is a replacement sent under the extended warranty for the SENNHEISER Momentum True Wireless 2, which I purchased a long time ago. I already own the IE900, and I listened to this once just to try it out. Naturally, the IE900 has better sound quality, and since I won't be using the HD600, I'm putting it up for sale. Used only once (for about 3 minutes), so there are no scratches, stains, or odors. Instant purchase is OK, so please consider buying it. Sennheiser Headphones High sound quality HD600 HD620 HD650 HD660