Why we reduce its size? Since the ergo mouse was launched we always recieved feedback like "too big" "not for my hands" "large for me" from our buyers. After long discussion we decide to size down the mouse. We are listening to the voice of our customer, if you have any feedback about the new updates please contact us on Amazon. Note: Unless stated in the title, products still are old version (old size). | Ergonomic Design: The ergonomically vertical handshake position reduces muscular strain and the pressure on your wrist, while your thumb is positioned comfortably on the thumb rest. | Plug and Play: Reliable wireless connection using a plug-and-play USB dongle, wide working range of a radius up to 32 feet, no additional driver needed. | Comfort Shape for Medium or Large Grip: (Dimensions:11.8cm/4.6in*7.5cm/3in*5.8cm/2.2in)The ergo mouse can help you work better and faster with a perfectly-crafted full-size shape designed for the large palm (even over 7.5- inch palm). | Ultra-Quiet Clicks & Well-Placed Thumb Controls: No more annoying click noise to create better, quieter environment for you and those around you. Create and work more intuitively and effortlessly with the ideally placed front and back buttons. | Premium Long-Lasting Battery Life (Battery NOT included): Only one AA battery needed, it can work up to 16 months thanks to auto-sleep power saving mode and on/off switch button. Note: The battery life may vary based on use and computing conditions.