Lately, Chinese mouse manufacturers such as Darmoshark, DELUX, or Zaopin have lowered the entry point for wireless mice considerably, as good 1000 Hz mice are typically available for around $50. 4000 Hz options, however, still carry more of a premium, such as the Darmoshark M3 4K at $69.99, for instance. With the AJ199 4K, Ajazz changes this, as at $55.99, it barely costs more than your average 1000 Hz wireless mouse.

Among the biggest downsides of higher polling rates is their impact on battery life. As a rule of thumb, doubling polling rate will typically roughly half battery life. Hence, most mice rated for around 70 hours at 1000 Hz will often struggle to do more than 15 hours at 4000 Hz, which of course isn't exactly much. On the AJ199 4K, Ajazz has addressed this problem in the most straightforward way imaginable: Compared to the regular (non-4K) AJ199, battery capacity has been tripled from 300 to 900 mAh. Accordingly, Ajazz states a confident 300 hours of battery life, though this of course could only apply to a polling rate of 1000 Hz. Unfortunately, confirming or denying this figure is made somewhat difficult by the lack of a proper battery life indicator in the software. The one that is present in the software lacks any segmentation or a percentage, so at most one could "eyeball" the current charge, but since the indicator is rather small, too, a significant error would be present nonetheless, so gauging anything is simply impossible. Based on my experience with other mice using the same firmware/software solution as the AJ199 4K, I'd expect battery life at 1000 Hz to clear the 200 hours mark, but not the 250 hours one, at 4000 Hz, around 50 hours seem plausible. Of course, this is still plenty compared to other 4000 Hz wireless mice. In absolute terms, charging is fairly speedy on the AJ199 4K at just short of 0.4 A, though given the massive capacity, a full charge will still take relatively long. Unfortunately, the charging cable makes matters worse in this regard: Aside from being fairly stiff, it also is very short at just 1.45 m. Hence, depending on how far away from the mouse one's PC is, the lack of cable slack may restrict mouse movement even further.

Despite the increase in battery capacity, the AJ199 4K stays lightweight at 63 g. The structural design too is competent, as there is only minor creaking but no flexing of the shell when applying lateral pressure, and actuating the side buttons by pressing below them is impossible no matter how much force is used. Unfortunately, my unit suffers from a major rattle, the culprit of which is the CPI button found on the bottom of the mouse. This button is loose to where during gaming, when moving the mouse rapidly for flick shots, the rattle can be easily heard, even with the game sound playing. Having taken a look at the design of the CPI button during disassembly, I believe this to be a design flaw, and therefore would expect the issue to be present on every unit, and if not initially then at some point later in time.

For the main buttons, Ajazz has opted for switches from Huano (transparent blue shell, pink plunger). In theory, these should provide a snappy and firm button response, but on the AJ199 4K, it is somewhat diluted by the moderate to high pre-travel present, though post-travel at least is low, and lateral movement only becomes noticeable if specifically provoked. Outfitted with Huano switches, the side buttons fare better, as pre and post-travel are low, and actuation even across their entirety. For the scroll wheel, a TTC Gold encoder sees use, which has been seen on several releases from Pulsar and LAMZU as well before, and which typically is rather noisy yet tactile. On the AJ199 4K, it sure is noisy, yet tactility is nowhere to be seen, as the separation between steps is lacking. Lately, I've seen similar cases on the Darmoshark M3S Varun and Waizowl OGM Pro as well, so either TTC's quality control leaves something to be desired, or Ajazz didn't do any binning. Either way, the scroll wheel feels shoddy and, for lack of a better word, cheap. The feet are made of regular black-dyed PTFE, which is why glide accordingly falls short of most competitors.

The AJ199 4K uses the same firmware/software solution from CompX that has also been used on releases from Pulsar, LAMZU, or recently Incott. In fact, the version number is almost a match with the Incott HPC01M Pro, which is why performance is near-identical, too. This is notable in that the HPC01M Pro specifically had issues when using the optional USB high-speed 4K Wireless Dongle, which is the default on the AJ199 4K. In particular, the AJ199 4K suffers from the same polling instability, and it applies to all polling rates and is particularly pronounced at 4000 Hz, as polls frequently are late by 3 ms and more, worsening consistency considerably in the process, despite the interval average coming out at 0.25 ms. Another issue that is exclusive to the AJ199 4K relates to the sensor run mode. At polling rates of 1000 Hz and below in wireless operation, the software allows setting the sensor run mode, either to "LP" (low power) or "HP" (high performance). From a performance standpoint, HP mode would theoretically be preferable over LP mode, as motion delay is roughly on par with the Logitech G403 (control subject), but polling outliers are very common when using HP mode, negatively affecting motion delay in the process. While LP mode isn't unaffected, both the frequency and magnitude of the off-period polls are significantly higher when using HP mode, leaving LP mode as the more consistent yet less responsive choice.

These issues aside, the raw numbers are far from bad. In wireless operation at 1000 Hz, a click latency of 1.7 ms is averaged, which is lowered to 1.0 ms at 2000 Hz and 0.8 ms at 4000 Hz. Likewise, motion delay is excellent, as even in LP mode at 1000 Hz, parity with the G403 is achieved as long as MotionSync is disabled, enabling which adds roughly 0.5 ms worth of motion delay. By using HP mode at 1000 Hz, or 2000/4000 Hz, this gap widens further. In addition, CPI deviation is low, and general tracking without issue regardless of MotionSync being enabled or not.

All in all, it seems that in order to be able to offer the AJ199 4K at such a low price, Ajazz had to cut quite a few corners. Still, it is important to put things in perspective, as for $55.99 on Mechkeys.com, the AJ199 4K brings a lot to the table regardless. Hence, while I consider the Darmoshark M3 4K at $69.99 and VGN Dragonfly F1 Pro Max with its 4K dongle at $69.98 the better budget 4K mice, the AJ199 4K provides very good value for money regardless, and earns our Budget award.