Power-Over-Ethernet (PoE) HAT for Raspberry Pi 4B/3B+ is a Raspberry Pi HAT which can support PoE for your Raspberry Pi 4B/3B+.
Raspberry Pi 4B/3B+ generally uses USB type-C interface for power supply. Although they both have one ethernet interface for internetwork, it can not realize the power supply function. Now, with this PoE Hat, things will be different. I'm afraid the USB type-C cable will not be available anymore.
This PoE Hat for Raspberry Pi supports active PoE which includes IEEE 802.3af and 802.3at PoE standard protocol. As a matter of fact, there is a "handshake" between PSE(Power Source Equipment) and PD(Powered Devices) and the PD will not apply the power supply if the supplied voltage is not matched. It is quite safe for your Raspberry Pi.
The Hat is perfectly compatible with Raspberry Pi 4B and available for Raspberry Pi 3B+. The way to assemble the HAT on Raspberry Pi Hat is easy as well, you can view the procedure here.
PoE power output must be within the budget of the switch when powering multiple boards!!! STANDARDS COMPLIANT POWER OVER ETHERNET SWITCH REQUIRED!!!
The network switch or power sourcing equipment (PSE) must be compliant with the IEEE 802.3af or 802.3at PoE standard, particularly section 33.4.1 with regards to PSE electrical isolation of the leads.
"Passive PoE" (DC 24V or 48V) is not standards compliant and may cause damage to equipment.
Do not use this product in an enclosed case without active air circulation!!