Improve support for Logitech MX Ergo's "precision" button

Author: daaaaaaaaanielCreated Sep 16, 2026Updated Sep 16, 2026

Details

I'm using a Logitech MX Ergo mouse.

Vendor ID: 1133 (0x046d)
Product ID: 45085 (0xb01d)

One of the buttons on this mouse is not properly supported. The MX Ergo mouse has 5 buttons that should be usable, but only 4 of them are actually supported in Karabiner. The fifth button is referred to as the "precision" button within Logitech's documentation for the product.

The "precision" button is detectable in Karabiner-EventViewer. Pressing the "precision" button produces this output:

[
  {
    "timestamp": "2026-09-16T16:49:58.297+03:00",
    "type": "unknown",
    "value": "  237",
    "usagePage": "65347 (0xff43)",
    "usage": "   -1 (0xffffffff)"
  },
  {
    "timestamp": "2026-09-16T16:49:58.297+03:00",
    "type": "unknown",
    "value": " 2815",
    "usagePage": "65347 (0xff43)",
    "usage": "   -1 (0xffffffff)"
  }
]

Releasing the fifth button produces this output:

[
  {
    "timestamp": "2026-09-16T16:52:03.071+03:00",
    "type": "unknown",
    "value": "    0",
    "usagePage": "65347 (0xff43)",
    "usage": "   -1 (0xffffffff)"
  },
  {
    "timestamp": "2026-09-16T16:52:03.071+03:00",
    "type": "unknown",
    "value": " 2815",
    "usagePage": "65347 (0xff43)",
    "usage": "   -1 (0xffffffff)"
  }
]

Source: pqrs-org/Karabiner-Elements