Instruction: Extract the value of the target attribute from the given product information and output it along with the corresponding source.

Input:
Product title: Gigabyte GM-ECO600 Long-Life Wireless Laser Mouse
Product description: GIGABYTE ECO600 Long-life wireless laser mouse has an expected battery life of up to 12 months.
Product feature: Long battery Life up to 12 months., Intuitive +/- DPI switching buttons., 5 customized buttons - assign button function through GIGABYTE Sim software., 3 stage blue LED DPI indicator - 800 / 1200 / 1600 DPI, Comfortable Rubber Grip.
Product brand: Gigabyte
Target attributes: Number of Buttons
Answer: attribute: number of buttons
value: None
source: None