Logitech MX Master 4 Mouse Spotted with an Extra Button

The unannounced Logitech MX Master 4 has been spotted in the European Union Intellectual Property Office (EUIPO) database, giving us a first look at its design and some construction details. Based on the published images, Logitech seems to be sticking close to the proven design of the MX Master 3 and 3S. The overall shape and layout of main elements are retained, but there are a few interesting tweaks.

The most noticeable addition is an extra button on the side panel. Its function is still unknown: some speculate it will simply be another programmable key, while others suggest it might integrate with new smart features. The thumb rest area has also changed significantly, now featuring a large button that takes up almost the entire space, which should impact usability.

Furthermore, the battery or connection status indicator has been relocated beneath the main scroll wheel, next to the MagSpeed mode-switching button. The side scroll wheel also appears slightly more pronounced in the images, and the primary buttons have been subtly reshaped. Technical specifications, materials, and pricing remain unknown for now. The mouse has already been spotted in Brazil's certification database, and leaked marketing materials suggest an official launch is likely imminent.