Clearly Superior Technologies, Inc L-Trac (CST2545-5W) USB Wired Laser Ergonomic 5-Button Trackball with 2 External Buttons Included - Made in the USA Package Includes: CST2545-5W Trackaball and 2 - CST S-Button External Switch Buttons with 8 - urethane feet & 8 - multi slick squares Width 3.75" (9.5cm), Length 6.75" (17.1cm), Height 1.75" (5cm) / Ball Size: 2.25" Trackball Resolution: User selectable 400, 800, or 1600 counts per inch Made in the USA Trackball Buttons: 3 (programmable) + 2 External Buttons (programmable) which plug into trackball switch jacks for a maximum of 5 buttons