Você precisará de um peso de 1kg e outro de 2kg.
A explicação é nessa linha do que o @MarcioMO falou:
If you have to calibrate your Timemore Black Mirror, you need to hold the timing button located on the display screen’s left side.
While holding the timing button down, you need to press repeatedly the power button located on the right side.
When the screen starts to act “weirdly,” you can release the timing button and then finish with a single click on the power button.
This frantic button pressing, as crazy as it sounds, puts the Timemore into calibration mode. The screen will then prompt you to place 1kg and 2kg weights onto the scale surface.
Aqui tem um vídeo durante a calibração