Driver-wise, Mionix stuck with what they know works. The driver suite is simple to navigate and allows you to quickly set your mouse up however you want. Like we saw on previous IR LED gaming mice from Mionix, you can adjust the lift-off distance, which is a great touch in my opinion as it is a parameter that needs to be tweaked to your particular gaming surface to maximize performance.

Performance

Mionix went with a slightly smaller shell for the Castor, which makes it good for people with small-to-medium sized hands and those wanting something nimble for a claw-type grip. Using the Castor with a palm-type grip is also pretty comfortable, but the comfort level will depend a bit on your hands' size. As we have come to expect from Mionix, the button layout is perfect. Sensor placement is also correct in that it has been placed right in the middle, which means it does not exaggerate movement when you articulate your wrist.

In terms of weight, the Castor is about as heavy as the Avior, retaining a 50/50 weight distribution, which makes it feel well-balanced in midair. The center of gravity could have been moved forward a bit to make it better for people using a palm-type grip, where you want the center of gravity to be between your thumb and pinky finger.

New for the Castor is the upped performance of the IR LED sensor we first tested in the Avior and Naos 7000 mice. The Avago ADNS-3310 has now been beefed up to 10000 DPI, which usually means it is running customized firmware that uses more of the sensor's area. At 10000 DPI and 1:1 sensitivity, it still feels precise, but is impossibly fast on even a WQHD (2560x1400) monitor. This was obviously also the case with the 7000-8200 DPI mice we tested. The real performance advantage of the ADNS-3310 sensor is that it does not suffer from positive acceleration like its laser-sensor counterparts, which is something most low-to-medium sensitivity gamers will feel as they game.

Tracking is perfect on our standard black QPAD and CM Storm surfaces. The only weakness of the IR LED sensor is that it does not track at all or very irregularly at best on reflective white surfaces. Grey mouse mats do not seem to cause the issue. The IR sensor's inherent sensitivity to reflections and color is something to keep in mind while selecting a surface for the Castor and other 3310-equipped mice.