Proteus Core allows you to change the weight, balance, and enables you to adapt to wherever you choose to play. Customize it to the way you game and make it yours! Fine tune Proteus Core to your playing surface for better accuracy, precision and responsiveness. A quick tuning process, and you are battle ready. Allows you to change the weight, balance, and enables you to adapt to wherever you choose to play. Helps you be an unstoppable force in low or high DPI. So buy this and Get $20 promo eGift card with the purchase of the Logitech G502 Tunable Gaming Mouse with FREE Gaming Mat for just $79.99! Free shipping!