J-DEAL&reg; Scroll Endurance Wired Mouse Ergonomic Vertical USB Mouse with Adjustable Sensitivity (600/1000/1600 DPI), Removable Palm Rest & Thumb Buttons - Reduces Hand/Wrist Pain Unique ergonomic design with removable palm rest to reduce hand and wrist pain Two thumb buttons can be used for back/forward browser navigation Driver free 3-mode DPI shift:600/1000/1600DPI adjustable High-resolution optical sensor with adjustable sensitivity for accuracy and responsiveness Scroll Wheel lifetime:200,000 circles/ Button lifetime:3 million times