Razer Basilisk V4 Pro: New AI Button Disrupts Thumb Ergonomics

Razer has updated its Basilisk gaming mouse line for the first time in two years, introducing a new AI button that complicates the physical layout of the device. The Basilisk V4 Pro launches at a price of $169.99, available in black and white. While the update extends battery life and reduces weight, the addition of two new programmable buttons has altered the thumb control cluster in a way that affects usability for many users.

The mouse now features twelve total programmable buttons, up from the previous count. A third thumb button has been added in front of the existing two, which opens Razer's AI prompt by default. A separate button located beside the left mouse button switches profiles. According to a review by Tom's Hardware senior editor Sarah Jacobsson Purewal, these additions create ergonomic challenges. The mouse measures 5.02 inches in length, placing the profile button at the front edge. Purewal noted that this position is too far to press comfortably for individuals with medium-sized hands and long fingers.

The placement of the new AI button presents a larger issue for thumb ergonomics. Because the AI trigger is the same size as the other thumb buttons, it pushes the remaining cluster backward. This leaves the first thumb button, labeled MB4, too far away to reach comfortably. Although the buttons can be remapped, Purewal found that all three thumb buttons felt slightly off after the change. The review questioned whether every mouse and keyboard requires a dedicated AI prompt button.

The V4 Pro is lighter than its predecessor. The black version weighs 3.53 ounces, a reduction of nearly half an ounce from the 3.95 ounces of the V3 Pro 35K. Purewal observed that while the mouse is still far from ultralight, it is easier to pick up. The tilt wheel offers two tactile modes with 24 and 48 steps, along with a free-spin mode. The free-spin setting was described as too sensitive and prone to backscrolling, while the precision tactile mode received praise.

Performance specifications include the Focus Pro 50K optical sensor, which reaches 50,000 DPI and 930 IPS. The sensor tracks on most surfaces, including glass at least 4mm thick. The fourth-generation switches are rated for more than 100 million clicks and produced no misclicks or double-clicks during testing. Purewal stated that the shape suits a range of games from MMOs to competitive shooters, though it may not be ideal for top-level competition.

Battery life has increased from 150 hours on the V3 Pro 35K to 200 hours at 1,000 Hz over 2.4GHz. At the maximum polling rate of 8,000 Hz, battery life falls to 54 hours. The mouse connects via 2.4GHz wireless, Bluetooth, or USB-C. It launches alongside the Mouse Dock V2 Pro, which sells separately for $69.99. The dock features an integrated 8,000 Hz receiver and eight RGB zones, and it is compatible with several older Razer mice.

The box includes a USB-A dongle, an adapter, and a 6-foot braided cable. It does not include Razer's flexible HyperFlex cables or grip tape. The V4 Pro retains the familiar right-handed contoured shape and bright RGB lighting from previous models. The previous update to the line was the Basilisk V3 Pro 35K in October 2024, which paired the V3 Pro with a new sensor.

Purewal recommends the Basilisk V4 Pro for players who want more functionality than a stripped-down shooter mouse but do not want a button-heavy design. The review identifies the feel, lower weight, and battery life as strengths. The drawbacks cited are the AI button's effect on the thumb-button layout, the price, and the mouse's slightly large size. The device is positioned between the DeathAdder V4 Pro and the more button-laden Naga V3 Pro.