Build Quality

Overall build quality is very solid. There is no rattle when shaking the mouse. When applying lateral pressure, minor creaking, but no flexing of the shell can be observed, and activating the side buttons by squeezing the sides isn't possible. Lastly, no accidental clicks occur when slamming the mouse down.

Buttons

Main buttons on the M42 are very good. Pre-travel is low and post-travel is moderate, and coupled with the firm buttons, click feel is snappy. While the buttons are separated from the shell, lateral button movement is as low as physically possible. Button stiffness is light and Omron D2FC-F-7N (OF) (20M) switches are used.


Side buttons are very good. While not that great on the M4, they're much improved on the M42. There's still some pre-travel, and the actuation point isn't entirely even, but post-travel is low, and the overall click feels nice and snappy. Button placement and size is great as actuation is possible very easily by rolling one's thumb over these. A set of Huano switches (yellow plunger) is used for these.

At the top of the mouse is a single button for cycling through the available RGB lighting modes. Its click feel is good, and another Huano switch (yellow plunger) is used for this one. On the bottom of the mouse is another button for cycling through the color-coded CPI levels, along with a slider for the polling rate. Quality of either is fine.

Scroll Wheel

The scroll wheel is excellent. Scrolling up or down barely produces any noise, and the individual steps are quite nicely separated, resulting in above average tactility. Furthermore, the wheel provides some resistance while scrolling, which makes for a greater sensory experience than with most other wheels. The encoder comes from F-Switch. The middle (scroll wheel) click requires medium to high force for actuation and uses a Huano switch (blue plunger).

Coating

Much like the M4, the M42 has a smooth UV-treated matte coating all over. It doesn't attract fingerprints, dirt, or the likes too much. It's easy to clean, and there are no signs of wear left after doing so. All in all, an excellent coating.

Button Sound Test

Disassembly

Disassembling the M42 is easy. Remove all the skates and unscrew the four screws—top and bottom shells are now easily separated. The internal design is equally simple. Nearly everything sits on a single PCB. The side-button PCB is screwed to the top shell and connected to the main PCB through a 4-pin JST connector, and an auxiliary PCB next to the scroll wheel provides scroll illumination. The main PCB is affixed to the bottom shell with three screws. All PCBs are very thin in order to save as much weight as possible. The MCU is a WTU301, same as for the M4.


As for the soldering and general quality of the PCBs, I'm unable to find any noteworthy flaws.