Bose’s email marketing team might have accidentally revealed an upcoming product ahead of schedule. Some hawk-eyed recipients of the company’s newsletter noticed something a little odd about the headphones featured in the image above: there’s a new button that doesn’t exist on Bose’s flagship noise-cancelling QC35 headphones.

The added, pill-shaped button is on the left earcup in the same place where volume controls and the multi-function button are on the right one. The image’s filename, email_QC35upgrade_img3.png, further fuels speculation that we’re looking at a revised version of Bose’s $350 cans, which were originally unveiled in June of last year

Until Bose properly announces these, there’s no telling exactly what the button does. My hope is that it might allow users to temporarily disable the noise cancellation or splice in some outside audio when they need a better sense of what’s happening in the world around them. That’s among our favorite features of Sony’s MDR-1000X, one of the QC35’s main competitors.

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The most recent firmware update for the QC35 headphones allows users to customize the level of noise cancellation between high, low, and off. This can only be changed using Bose’s smartphone app, however; adding a button to toggle between the modes would be a more convenient solution. But for now, the new button’s purpose is a mystery.

The Verge has reached out to Bose for comment.