CST1350SA USB-PS/2 Wired Ambidextrous Ergonomic Colorful Switch Adapted Trackball - Made in the USA Width 3.75" (9.5cm), Length 6.75" (17.1cm), Height 1.75" (5cm) / Ball Size: 2.25" This model does NOT contain a Scroll Wheel Buttons: 2 (programmable) + Middle (Draglock) OR 3 switch jacks which allows users to plug in three external buttons which disable the corresponding on-board buttons for added customization Made in the USA Installs using PS/2 or USB interface port.