Wireless Ergonomic Trackball Mouse with Adjustable Angle. PERIMICE-720 is an ideal product for those customers need to have an ergonomic desktop environment. With its 2 adjustable bases, the customer has the option to choose from 0, 10, to 20 tilt degree according to their preference. The default purple trackball provides another refreshing appearance, and the customer has the option to purchase a replacement trackball from the Perixx multi-color trackball family.