Build Quality

Overall build quality is solid. When shaking the mouse, a rattle comes from the CPI button. When applying lateral pressure, no creaking or flexing of the shell can be observed. Activating the side buttons by squeezing the sides is impossible. Lastly, accidental clicks do not occur when slamming down the mouse.

Buttons

Main buttons on the Helios II Pro are decent (right button) to subpar (left button). Pre-travel is moderate to high, post-travel is moderate, and button response is noticeably dull and muted, with the left one being the greater offender. The buttons are visually separated from the shell, and lateral button movement is low to moderate when provoked. Button stiffness is medium. A pair of TTC Optical Gold (100 M) switches are used for these.


Side buttons are very good (forward button) to decent (back button). The forward button has low pre and moderate post-travel, whereas the back button has moderate pre and high post-travel, to where the button can be pressed in quite a bit past actuation. The pressure point is even across the entirety of these. Button size and placement are good, as actuation is possible rather easily by rolling one's thumb across. A set of Huano switches (white plunger) are used here.

At the bottom of the mouse is a single button for cycling through the set CPI steps, which works fine. A seemingly unbranded tactile switch is used for this one. In addition, a slider switches between 2.4 GHz, Bluetooth, and off-state, which too works fine.

Scroll Wheel

The scroll wheel is good. Noise levels are high when scrolling down in particular, but tactility is good, with fairly distinct steps allowing for controlled scrolling. The encoder comes from F-Switch (brown, black core) and has a height of 12 mm. The middle (scroll wheel) click requires medium force for actuation. An elevated Huano switch (blue plunger) is used for this one.

Surface

The Helios II Pro 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 Helios II Pro is easy. The screws are located beneath the front and rear skates. After removing those, the top and bottom are quite easily separated, though some caution is advised not to rip the cable connecting the two.

The internal design is very efficient. The side buttons sit on their own PCB screwed to the top shell and connected through a 3-pin connector. The battery is glued to the back of the bottom shell. Everything else sits on the very thin and compact main PCB, which is affixed to the bottom shell by three screws. The MCU is a Nordic nRF52833, whose datasheet is found here. Production date of the main PCB is the 35th week of 2023.


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