Heat pump monitor RaspberryPi HAT includes:
Does not include: RaspberryPi, spacers, terminal blocks for digital IO and pulse counting.
See full product details and how to use this HAT here:
https://github.com/openenergymonitor/HeatpumpMonitor/tree/master/HeatpumpMonitorPi
For a guide on selecting a suitable MBUS heat meter, see:
https://github.com/openenergymonitor/HeatpumpMonitor/blob/master/selectingheatmeter.md