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. Activating the side buttons by squeezing the sides is impossible. Lastly, accidental clicks when slamming down the mouse do not occur.

Buttons

Main buttons on the Model O 2 Pro 4K/8KHz Edition are good to very good. Both buttons have moderate pre but low post-travel, and button response is rather firm and snappy. Despite being visually separated from the shell, button movement is low even when provoked. Button stiffness is medium. A pair of optical switches from RAESHA (100 M) are used here.


Side buttons are very good (forward button) to decent (back button). The forward button has low pre and post-travel, along with even actuation, whereas the back button has moderate pre-travel along with uneven actuation, though post-travel likewise is low. Button size and placement are quite good, as actuation is possible rather easily by rolling one's thumb across. A set of surface-mounted switches from Huano (beige plunger) are used for these.

At the top of the mouse is a button for cycling through the set CPI levels, which feels decent. Another Huano switch (green plunger) is used for this one. A simple on/off slider is found at the bottom, which works fine.

Scroll Wheel

The scroll wheel is very good. Noise levels are appreciably low, though tactility is merely slightly above average, as the steps are somewhat lacking in separation. The encoder comes from F-Switch (yellow, green core) and has a height of 11 mm. The middle (scroll wheel) click requires medium force for actuation. An elevated Huano switch (green plunger) is used here.

Surface

The Model O 2 Pro 4K/8KHz Edition has a matte surface all over. Grip is fine, and it doesn't attract fingerprints or dirt too much. It is easy to clean, and there are no signs of wear left after doing so. All in all, excellent materials.

Button Sound Test

Disassembly

Disassembling the Model O 2 Pro 4K/8KHz Edition is very difficult. First, the two rear skates along with the screws underneath them need to be removed. Second, the rear top shell needs to be cautiously removed, which can be very challenging, giving access to two downward facing screws towards the rear. Next, the main button pieces need to be dislodged, which shouldn't be much of a problem, in turn giving access to another set of downward facing screws towards the front. Finally, the clips at the sides and front need to be dislodged, which is relatively easy.

The internal design is fairly efficient. The side buttons are slotted vertically into a plastic assembly part of the bottom shell and connected through a 3-pin connector to the main PCB, while the battery is slotted vertically towards the rear. Everything else sits on the very thin main PCB, which has been affixed to the bottom with three screws. Two MCUs are used: A WCH CH32V307 RCT6, which provides a USB high-speed PHY and whose datasheet can be found here, along with a Nordic nRF52840 for wireless communication, whose datasheet is found here. The Bluetooth capability of the latter chip remains unused. The production date for all PCBs is the 26th week of 2023.


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