4 Sizes Copper Pads: 15 x15 x0.5mm, 15 x15 x1mm, 20 x20 x0.5mm, 20 x20 x1mm. EACH SIZE 10PCS, 40Pcs IN TOTAL. Material: Pure copper, featured high thermal and electrical conductivity. Smooth surface, no burr on the edge. Recommended Use: Heat conduction and gap filling between the graphics card and the thermal module to improve heat conduction and reduce the graphics card repair rate. Applications: Copper coolers can be used for passive heat dissipation of notebook computer, CPU, GPU, RAM, VGA, IC chip, etc. Function: The thermal heatsink copper is the perfect heat dissipation for your DIY Arduino projects.