40mm

BLUE LED BACKLIGHTING & BREATHING LIGHT EFFECT: Features blue LED backlighting on both keyboard and mouse. 3 brightness setting for keyboard to improve visibility in low-light condition and breathing light effect option on keyboard.
MULTIMEDIA KEYS & WIN LOCK: 104 standard keys, dedicated 10 multimedia keys to control volume, music, homepage, & email. WIN key can be disable for gaming to avoid disturbing gaming time.
5 + 1 (SCROLL WHEEL) BUTTONS: DPI button for 4 changeable levels of dip resolution (800/1200/1600/2000), forward button, backward button, right mouse button, left mouse button, & large high-precision scroll wheel.