1, main month change: it is generally changed in three months: 1, and in May and September, the main contract will be changed to the month before the delivery month. For example, the contract of 190 1 will become new when the transaction volume exceeds 1809 at the beginning of October1August.

2. For the monthly price difference, according to the delivery rules of the exchange, the standard warehouse receipt of 1 1 rubber is cancelled every year, so the price difference between 1 9 contracts is extremely unstable, one is new rubber, the other is old rubber, and the monthly price difference between 1-5, 5-9 is relatively stable, or even more.

Have a good time.