Build Quality

Overall build quality is very solid. There is no rattle when shaking or tapping the mouse. When applying lateral pressure, no creaking or flexing of the shell can be observed. Furthermore, it is not possible to activate the side buttons by applying lateral pressure or to activate the main buttons by applying pressure to the lower top shell, which is impressive given the M4 is covered in holes. It seems as if Xtrfy has paid special attention to the structural integrity of the M4, as the shell walls are rather thick and further strengthened by several elements providing structural support. Lastly, when slamming the mouse down, no accidental clicks occur.

Before I delve further into the button quality, a short disclaimer: This review is based on a pre-production sample with non-finalized tooling. I've been told by Xtrfy that both the quality of the main and side buttons will be much improved for finalized mass production. For now, I'm unable to verify this claim, but I'll update the review accordingly if I get the opportunity to do so.

Buttons

The main buttons of the M4 are good, but not great. The click feel is nice and satisfying, but there is slight pre-travel and moderate post-travel on both buttons. They're fairly light clicks, although not as light as (e.g.) Logitech clicks. Notably, there is only minor horizontal wobble on both the left and right click (more so on the left one). Chinese Omron D2FC-F-7N (OF) (20M) are being used for the main buttons. These can be found on the Glorious Model O (among others) as well.


Similarly to the main buttons, the side buttons are good but not great. Click feel is a bit mushy, largely due to the moderate amount of pre- and post-travel on both the forward and back button. A lever design is used for the side buttons, which isn't the best choice. As for their placement, the side buttons sit fairly high (expected from a right-handed ergonomic design), which coupled with their smaller size can make it difficult to activate them by simply rolling the thumb over them. Yellow Dot Huano switches are being used for the side buttons.

On the bottom of the mouse is a slider which controls the polling rate (125 Hz, 500 Hz, or 1000 Hz), as well as a button which controls CPI levels (cycle). Neither button can be remapped. On the top is a button which controls the lighting of the mouse. The switch for the latter is yet again a Yellow Dot Huano.

Scroll Wheel

The scroll wheel is excellent. Easy to scroll, very quiet when scrolling up or down, with tactile steps, and a nice texture on the wheel, the scroll wheel of the M4 is easily one of the best I've encountered so far. The middle (scroll wheel) click requires less than moderate force for actuation. The encoder is a brown one from F-Switch (known from the Glorious Model O), while the button switch is another Yellow Dot Huano.

Coating

The M4 is covered in a matte UV coating all over. It's very grippy and doesn't attract finger prints, dirt and the like too much. It's easy to clean, and there are no signs of wear left after doing so.

Button Sound Test

Disassembly

Taking the M4 apart is fairly easy. Bottom and main shell are held together by four screws, which are located beneath the four bottom mouse feet. The main PCB holds everything but the side buttons, which sit on their own PCB that is screwed into the top shell and connected through a 4-pin JST connector. The cable is routed below the main PCB, which is affixed to the bottom shell with two screws. It's a fairly clean and elegant design with little to criticize. Curiously, the side buttons PCB is a fair bit thicker (1.2 mm) than the main PCB, which is 0.8 mm thick. I can only assume that this was done for reasons of structural integrity.

Unfortunately, I was unable to identify the MCU myself. The markings are both difficult to read and non-conclusive even after figuring them out. However, I've been told by Xtrfy that the MCU is a WTU301 (full specification: WTU301 N36C-C 1917-C S2SF9), which is a 32-bit ARM CPU.


Interestingly, both the main and the side buttons PCB bear the same manufacturing date (2019-8-19), which gives reason to believe that there weren't any major issues or obstacles during the development phase. As for the soldering and general quality of the PCB, I'm unable to find any noteworthy flaws.