OPTICAL TRACKING TECHNOLOGYThe ELEOM "EX-G series" trackball provides precise cursor movement for superior accuracy so you can get where you want on the screen quickly with less hand movement, improving productivity and efficiency. This mouse is designed for a LEFT-HANDED person. FUNCTIONAL 6 BUTTONSYou can assign favorite function to each button by using "ELECOM Mouse Assistant" ELECOM Mouse Assistant Software will be available to download from ELECOM NET website. DPI CURSORDesigned with a high-performance gaming optics system sensor and lens. The DPI button can easily change between 750(LOW) and 1500(HIGH) DPI, making the movements of your cursor faster or slower. RED BALL FOR THE BEST OPTICAL TRACKING For the tracking accuracy and the best sensor, this item uses a RED BALL. RED COLOR sensing provides more accuracy for current optical tracking technology, a must for high-performance gaming optics system sensors. Y