VOL in the futures chart refers to the futures trading volume.

Futures trading volume refers to the bilateral cumulative quantity of a futures contract traded on the same day, and the unit is "hand".

1. The basic (minimum) trading unit of futures is (one) contract, commonly known as "hand".

2. The turnover is the number of contracts that have been concluded, which is calculated bilaterally (buying and selling), so it must be even.