roller:

Advantages: beautiful and novel. The appearance of the sliding cover machine has the advantages of both the candy bar machine and the flip machine: when it is not in use, it is a candy bar machine; once it is used, pushing and pulling the cover is equivalent to opening and closing the cover of the flip machine.

Disadvantages: The slide rail is easily damaged, and the cable is easily broken. The operation is a little cumbersome, because it needs to be used in conjunction with the upper and lower keyboards.

roller:

Advantages: convenient and practical, strong anti-fall ability, easy to carry, easy to operate with one hand.

Disadvantages: not trendy enough, it is not easy to show yourself through the appearance of the mobile phone. Also, when you put your phone in your pocket, if the keypad is not locked, it is easy to broadcast the number, causing unnecessary trouble. In addition, the screen is also relatively easy to wear, but since there is a film, this problem does not matter.

spring:

Advantages: novel and fashionable.

Disadvantages: the spring part is easy to break for a long time; the screen is easy to wear and tear, with the film, this problem does not matter.