They modeled the pieces after Chinese coins with square holes in the middle. The holes allowed people to string large amounts of coins together. In general, they would add 100 coins per string.

The one confirmed Ban Liang coin had a diameter of 2.3 centimeters and was 1 millimeter thick. The square hole in the middle measured 7 millimeters on each side. The characters for “Ban” and ...

I then found a Roman coin and another with my pinpointer in the same hole. 'I was so excited that ... it then just snowballed from there over a 4m square area and we found 50 coins in total ...