Logitech MX Keys technical glossary

Scissor switch mechanism: Key mechanism of low-profile keyboards such as the MX Keys: an X-shaped plastic hinge guides the key's vertical travel. It keeps the key level wherever you press it.
Rubber dome: Rubber (silicone) dome under each key: it provides the resistance you feel and pushes the key back up. When pressed, it deforms and closes the contact on the membrane underneath. A tired or misplaced dome makes the key feel mushy. Our used keys ship without a dome, which stays on the keyboard; domes are sold separately.
Hinge clip (scissor hinge): X-shaped plastic part that clips between the key and the keyboard and guides its vertical travel. It breaks easily when a key is pulled off or refitted at an angle. Our keys come with theirs; on its own it costs €6.99 and fits the regular-size keys of the MX Keys, MX Keys S, MX Keys for Mac and MX Keys Mini (wide keys have their own mechanism).
Keycap: The visible plastic part you type on, bearing the character. It comes off and can be replaced individually with a fingernail or a spudger. Ours are original used keys, taken from dismantled keyboards.
Stabilizer bar: Metal rod fitted under some wide keys, such as the spacebar, so they go down level even when pressed at one end. Often overlooked when replacing a long key: check it is clipped into both holders.
Logi Bolt: Logitech USB receiver launched in 2021 to succeed Unifying, built on Bluetooth Low Energy. It is the MX Keys S receiver. The two families are not cross-compatible: a Unifying keyboard will not pair with a Bolt receiver, nor the other way round.
Unifying receiver: Logitech's long-standing USB receiver, launched in 2009 and recognizable by its orange logo. It accepts up to 6 compatible devices on a single dongle. It is the receiver of the 2019 MX Keys; Logitech has moved its recent models to Logi Bolt.
Easy-Switch: Logitech feature on MX Keys (keys 1, 2, 3) that switches between 3 paired devices, for example a PC, a Mac and a tablet. Each channel uses Bluetooth or the USB receiver (Unifying on MX Keys, Logi Bolt on MX Keys S). Switching does not require re-pairing.
AZERTY / QWERTY / QWERTZ: European keyboard layouts, named after the first letters of the top letter row. AZERTY: France and Belgium. QWERTY: English (US, UK), as well as Spain, Italy and Portugal. QWERTZ: Germany, Switzerland, Austria. They differ in the position of a few letters and special characters. Each MX Keys is sold in one specific layout.
Actuation force: The pressure needed for a key to register a keystroke, expressed in grams. The lower it is, the lighter the typing; the higher it is, the fewer accidental keystrokes from merely brushing a key.
PCB (Printed Circuit Board): The keyboard's main circuit board, or "motherboard": it carries the controller and the radio (Bluetooth and USB receiver: Unifying on MX Keys, Logi Bolt on MX Keys S). It depends on the layout and on the PC or Mac version. When it fails, it is replaced as a whole: €14.99 for the AZERTY PC version in our catalog.
LiPo battery (lithium-polymer): Flat, lightweight rechargeable battery type fitted in the MX Keys. It dislikes high heat and freezing. If punctured or crushed it can catch fire: handle with care, and take it to a collection point at end of life.
Adaptive backlight: White key backlighting that adjusts to ambient light. It turns on as your hand approaches and off after a few seconds without typing, which saves battery. Present on MX Keys, MX Keys S and MX Keys Mini, absent on the K950.
USB-C: Reversible connector (it plugs in either way up) that charges the MX Keys, MX Keys S and MX Keys Mini. Day to day, the keyboard talks over Bluetooth or its USB receiver; the cable is for charging.
Bluetooth Low Energy (BLE): Low-power variant of Bluetooth, used by the MX Keys for wireless. It is easier on the battery than classic Bluetooth and works with recent computers, tablets and phones (Windows, macOS, iPadOS, iOS, Android, Linux).
Debouncing: Filtering of electrical bounce: when a key is pressed, the contact bounces for a few milliseconds, and the firmware merges those bounces into a single keystroke. If the filtering is badly tuned or the contact worn, a key can type twice ("double-typing").
HID (Human Interface Device): Standard protocol for input devices (keyboard, mouse, gamepad), supported natively by every modern operating system with no extra driver. That is why an MX Keys works on Mac, Linux or Windows without installing Logi Options+; the software is only needed for advanced features such as customization and Smart Actions.
SMD soldering: Surface-mount devices: an assembly technique where components are soldered directly onto the surface of the board. Replacing a single component takes microsoldering equipment; swapping the whole board is simpler.
Case screws: The screws that close the MX Keys case are hidden under the rubber feet: remove the feet to open the keyboard, then refit or replace them. We sell the complete set of 6 screws and replacement rubber feet.
Spudger: Flat plastic tool that unclips a key or component without scratching it or risking a short circuit, unlike a metal tool. Used to remove MX Keys keys and free broken hinges. €2.50 each in our catalog.