The DFRobot Black Aluminum Heatsink Kit for Raspberry Pi 4B is a heat dissipation solution for the Raspberry Pi 4B. The heat sink adopts a slotted design on the surface, which is more conducive to heat dissipation. It also comes with adhesive backing for easy installation. Features & Specs * Size * Black heat sink with adhesive (large): 40mm x 30mm / 1.57" x 1.18" * Black heat sink with adhesive (middle): 14.5mm x 10mm / 0.57" x 0.39" * Black heat sink with adhesive (small): 9mm x 9mm / 0.35" x 0.35" * The heat sink comes with adhesive * Black aluminum material