What does Jiangsu Mobile mean by introducing the B file of flow safety pericardium?

Is the latest mobile service, with two grades, 10 yuan package 100MB and 60 yuan package 2GB.

Then the problem is coming. If I exceed 2MB, will I be charged 10 yuan? There must be no!

Give a chestnut. If it only exceeds 2MB, the system will deduct it according to 0.29 yuan /MB, and only charge you 0.58 yuan.

When you use 10 yuan, that is, 10÷0.29≈34.5MB, the system will not charge you, and the remaining 100-34.5=65.5MB can be used for free!