Build Quality

Overall build quality is mostly solid. There is no rattle when shaking the mouse. When applying lateral pressure, minor creaking and significant flexing of the shell can be observed in particular around the intersection between the main buttons and sides. In fact, when applying pressure exactly at the top, the entire top contracts. 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 UltralightX are good to decent. Both buttons have moderate pre and high post-travel, though button response is rather firm and snappy nonetheless. However, especially when actuating the buttons towards the edges, a crunchy sensation is present. Being visually separated from the shell, the buttons can be moved laterally quite a bit when provoked, though this isn't noticeable during actual use. Button stiffness is light. A pair of Omron D2FC-F-7N (20 M) (OF) (China) switches are used here.


Side buttons are very good (forward button) to good (back button). Whereas the forward button has low pre-travel, the back button has moderate pre-travel, though post-travel is equally low on both, and actuation even across the entirety of these, resulting in a pleasing and snappy button response. Button size and placement are quite good, as actuation is possible rather easily by rolling one's thumb across. A set of surface-mounted Omron switches (blue plunger) are used for these.

A simple on/off-slider is found at the bottom, which is easily reached and works fine.

Scroll Wheel

The scroll wheel is good to very good. Noise levels are high, but tactility is quite good, as the individual steps are rather well-separated. The encoder comes from Kailh (gray) and has a height of 9 mm. The middle (scroll wheel) click requires medium to high force for actuation. A TTC switch (purple plunger) is used here.

Surface

The UltralightX 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. That said, both the engravings on the main buttons and the holes on the sides fetch dirt and grime rather easily, and removing it isn't always easy. All in all, good materials.

Button Sound Test

Disassembly

Disassembling the UltralightX is very easy. First, the two rear skates along with the screws underneath them need to be removed. After doing so, top and bottom shell are separated with ease.

The internal design is efficient. The side buttons sit on their own PCB vertically slotted into a plastic assembly that is part of the bottom shell and connected through an FFC to the main PCB. The battery is stuck to the bottom at the rear. Everything else sits on the very thin main PCB, which is affixed to the bottom by four clips, two of which are further affixed with glue, and while there are two additional screw posts, these too have been treated with glue. The MCU is a Nordic nRF52840, whose datasheet is found here. The Bluetooth capability of the chip remains unused. The production date for the main PCB is the 25th week of 2023.


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