CST2545-5W (L-Trac) USB Wired Ambidextrous High Performance Laser Ergonomic 5-Button Trackball (Black) - Made in the USA<div style="text-align: left;"><strong>[Product Information]</strong><ul><li id="replacementPartsFitmentBullet" class="aok-hidden" data-doesntfitmessage="We're not sure this item fits your " data-fitsmessage="This fits your "><span class="a-list-item"><span id="replacementPartsFitmentBulletInner"><a href="#" class="a-link-normal hsx-rpp-fitment-focus">Enter your model number</a>to make sure this fits.</span></span></li><li><span class="a-list-item"> Width 3.75" (9.5cm)， Length 6.75" (17.1cm)， Height 1.75" (5cm) </span></li><li><span class="a-list-item"> Ball Size: 2.25" </span></li><li><span class="a-list-item"> Resolution: User selectable 400， 800， or 1600 counts per inch </span></li><li><span class="a-list-item"> Made in the USA </span></li><li><span class="a-list-item"> Buttons: 3 (programmable) + 2 switch jacks (programmable) which allows users to plug in two external buttons (Sold Seperatly - CST S-Button External Switch) for a maximum of 5 buttons </span></li></ul></div><img src="http://ecx.images-amazon.com/images/I/31uFGkDdmTL.jpg" noproxy>