This is the Elecom trackball, the "HUGE." It's a trackball operated with the index and middle fingers. It has a large 52mm ball, providing a unique feel, and allows for comfortable fine work. I was mainly using a different trackball, so it hasn't been used much. (There's no wear and tear on the armrest, which appears with extended use.) This model connects via 2.4GHz wireless (USB dongle). Below is a copy of the text from the product page for your reference: Experience an unprecedented ball-handling feel with the 52mm diameter large trackball. The "HUGE" wireless trackball mouse features an index and middle finger operation type and is equipped with a palm rest to reduce wrist strain during long PC work sessions. By adopting a large 52mm diameter ball, this index and middle finger operated wireless trackball mouse "HUGE" allows you to move the pointer over a wider range with a single operation. A low-resilience palm rest made of memory foam is used on the top surface of the main unit, reducing wrist strain from long hours of PC work. The sensor that detects the movement of the trackball is equipped with a high-performance optical sensor of gaming grade. By thoroughly analyzing the color and coating thickness of the trackball suitable for the optical sensor and re-examining the trackball design from scratch, the ultimate pointer tracking performance has been achieved. Other features: Tilt wheel (horizontal scrolling), DPI switching Power: Battery operated