The lead tubes are:
- Kuru Toga 0.5 HB
- Kuru Toga 0.5 B
for example: https://www.amazon.com/Mechanical-Pencil-Lead-0-5mm-U05203B-33/dp/B00A3QHXAG/ref=sr\_1\_2?keywords=Mechanical+Pencil+Refills+kuru+toga&qid=1674543340&s=office-products&sr=1-2