Pi 4 Heatsink with thickness of 11mm: Geekworm 11mm embedded armor aluminum heatsink(P165-B), only compatible with Raspberry Pi 4 Model B 1GB/2GB/4GB/8GB Cooling Solution: Support installing raspberry pi 4 expansion board above the heatsink, so you can cooling down the raspberry pi 4 even when using with pi 4 expansion board(also support PoE board) Fan Supported: Support installing 30mm fan on heatsink when the heat dissipation of a single aluminum heatsink is not enough, further avoid overheat problem About Spacers: Only equipped with 4pcs M2.5X5+5mm spacers for the P165-B embedded heatsink, you may need to prepare extra standoffs or screws according to your need About Thermal Tape: Added 1pc thermal tape, which is unesential, only need it when there is a gap between pi & heatsink Better Cooling Solution: The theoretical value of the gap between the heatsink protrusions and the CPU, RAM and other chips of Pi 4 is 0mm; Strongly recommend to use CPU grease to get better heat dissipation WIKI for Reference: wiki.geekworm.com/P165