by 
It's hard to imagine how much better ultra-light wireless gaming mice can become. Since arriving fashionably light in 2019, they've become a mainstay of competitive gamers, thanks to their fast and manoeuvrable designs, high-end optical sensors and bulletproof 2.4GHz connections. The early models often used fully ventilated designs that sacrificed structural integrity, but seven years on we've reached a point where almost all of the major gaming brands have at least one great option: light, reliable, performant. Corsair has the Sabre, for Asus it's the Harpe Ace, while Razer's flagship duo are the ergonomic DeathAdder and the symmetric Viper.
It's into this backdrop that the £145/$160 Viper V4 Pro Wireless arrives. Unlike rival Logitech's X2 SuperStrike, it doesn't take a wild jump into novel button tech in search of a unique advantage; instead, it serves as the final destination of the path that Razer has been treading since debuting the first Viper mouse in 2019 - a mouse that's lighter, faster and longer-lasting.
Most of the gen-on-gen changes here are minor: it's nearly 10 percent lighter than the 2024 V3 Pro, has a new optical scroll wheel ideal for CS2 players, and micro-tracking is refined thanks to a new optical sensor and FrameSync tech (essentially VRR for mice, aligning polls with sensor frames). The biggest change though is battery life, which nearly doubles from 95 hours on the last-gen model to 180 hours on the V4 Pro. That's largely achieved through a smarter, more efficient wireless sensor, plus smaller gains elsewhere; the same iterative strategy also allowed for that 5g of weight savings through a smaller circuit board and other minor tweaks.
| Razer Viper V4 Pro | Razer Viper V3 Pro | |
| Weight (g) | 49 (Black) / 50 (White) | 54 (Black) / 55 (White) |
| Focus Pro Sensor | Optical Gen-3 | Optical Gen-2 |
| Max Sensitivity (DPI) | 50K | 35K |
| Max Speed (IPS) | 930 | 750 |
| Max Acceleration (G) | 90 | 70 |
| Max Polling Rate (Hz) | 8000 | 8000 |
| Switches | Optical Gen-4 | Optical Gen-3 |
| Switch Lifetime (clicks) | 100M | 90M |
| Scroll Wheel | Razer Optical Encoder | TTC Silver Mechanical Encoder |
| Max Battery Life (hours) | 180 at 1000Hz | 95 at 1000Hz |
| Dimensions (mm) | 127.1 x 63.9 x 39.9 | 127.1 x 63.9 x 39.9 |
Combined, these changes easily make the Viper V4 Pro the best mouse that Razer has ever made - and it's produced some absolute crackers in its day. The battery life change is by far the most critical, as it allows the mouse to be used in its top 8000Hz polling rate mode for a substantially longer period than most rivals - around 45 hours, versus just 17 hours for its predecessor.
And if you're at the standard 1000Hz polling rate, then even with 12 hours a day of usage, you're looking at a solid two weeks between recharges - or a full month if you have a more reasonable six hours daily. That helps ameliorate the loss of the charging dock that only stuck around for the initial Viper generation, as well as the lack of Bluetooth - normally a good way to stretch out longevity for non-gaming tasks. The lack of BT makes the Viper less of a great all-rounder you'd be willing to take on a train to get some work done, but for a mouse of this price perhaps you'd not be doing that anyway.
I also like the new "hemispheric" 2.4GHz dongle, which is a bit trickier to plug a USB-C cable into than a standard rectangular prism, but apparently has advantages in terms of connection strength. It also provides a spot for three LEDs along the front, which show you different coloured lights to indicate connection strength, battery life and polling rate.
The V4 Pro is also notable in what it doesn't change from the prior generation model. The shape is absolutely mirrored between the two, with 127x64x40mm dimensions that are comfortable for medium to large hands (mine are 20x10cm, for reference). Comfort curves remain in the left and right mouse buttons, while the side buttons are easily accessible with the thumb without having to change grips. I used a relaxed claw most of the time, but palm and fingertip grips worth well enough too. The buttons here noticeably louder than the near-silent X2 SuperStrike, but shouldn't annoy anyone used to more standard mechanical or optical mouse clicks. The underside of the mouse has two large skates, top and bottom, plus a ring around the sensor and a power/DPI button.
The Viper V4 Pro is the first Razer product to come with web app support, which you can see in the screenshots above. The overall layout is sensible, with good explanations for each setting and no download required. You can adjust DPI in one-unit increments, rebind keys, set polling rates between 125Hz and 8000Hz, and even account for a bit of rotation in your normal mouse grip (though testing this requires a separate download). However, I did notice that the web app linked to an older version of the mouse firmware (v1.03 instead of the otherwise-available 1.04), which is a bit of an oddity. Still, everything else worked well.
In terms of gaming and work performance, the Viper V4 understandably performed exceptionally. These low weight mice are exceptionally easy to move and stop with precision, and the sub-50g weight felt perfectly judged for my tastes. The shape was immediately familiar too, as I mostly use symmetric mice (including the older Vipers) outside of review periods, and I had plenty of fun tracking fast-moving Light 'Mechs in MechWarrior 5: Mercenaries, turning rivals into a fine mist in UT2004 Instagib and of course reminding myself just how rusty I am at Counter-Strike 2. For work, the mouse was comfortable enough to use for hours on end, and automatically clocking to 1000Hz when out of a full-screen game was a useful feature to conserve battery life.
There are plenty of mice to offer great performance though, and it was the efficiency to handle the increased power draw of 8000Hz polling for a useful period of time - days rather than hours - that made the V4 Pro much easier to live with than the average bear. I did find that the included cable wasn't as flexible as I prefer for using while the mouse was recharging, so I eventually got into the habit of keeping it plugged in with a better Asus cable instead; something akin to that OG dock to top up between sessions without having to plug in a cable would have been even better.
Ultimately, the Viper V4 Pro is an exceptional mouse with very little to disqualify it from recommendation, apart from its high-end price - which has already started to dip in the few months since it first launched. The shape, sensor and software are all well-tuned for a broad audience, and the battery life improvements are a game-changer for 8K.
That said, the V4 Pro doesn't introduce anything as alien or exciting as the bizarre-but-convincing haptic buttons that Logitech introduced with the X2 Superstrike - and that I think are likely to shape a lot of other mice going forward. Razer are instead sticking to a more conservative approach, one that doesn't risk alienating its core audience of FPS enthusiasts and lovers of high-end tech, and that's fair enough.
If you like ultra-lights, this is one of the premiere options and I highly recommend it. And if you don't have the budget for a £145/$160 mouse - understandable - then the earlier V3 Pro (£127/$110) is nearly as good overall, despite its shorter battery life. I'd also have a look at the Asus ROG Harpe 2 Ace (and its predecessor) and the non-Carbon Fiber version of the Sabre V2 Pro as two great alternative options.
Of course, if you have more specific requirements or want to know something more about the Viper V4 Pro, feel free to let me know in the comments below - or hit me up on Discord if you're part of the DF Supporter Program. I'm always happy to offer recommendations if I can!