E3D Revo™ HeaterCore
Watch out, some of them have a thermistor issue
In general, I really like the Revo. However, there is a problem with some of them with either the thermistor or the connector on the wires to the thermistor. Assuming your printer has basic safety features in the firmware, you will know it because it will shut off the heater and give an error message. If this happens, it's covered under warranty, so not a big deal. But until they resolve this issue, I'm docking two stars.