What is the difference between an expensive phone case and a cheap phone case? (Except for appearance)

I have changed the cases of my mobile phone three times. Let me talk about my feelings. The metal skin of the original case fell off after a year of use, and the buckle of the back cover was broken. So I bought a case worth more than 20 yuan. To be honest, except for the back cover, other parts of this case are almost useless. It is either too big or too small to match the movement, and there is also a screw eye that is tripped. Moreover, the panel is not made of black plastic at all. It is made of recycled plastic with a layer of black stickers on it. The keyboard is extremely difficult to use, so I had to give up and just use a back cover. But even this back cover is the same as the original one. There is color difference. The shell I bought later for more than 70 yuan is much better. The various parts are well integrated and the texture is also very good. Accordingly, it has been used for more than half a year and is still relatively new. Anyway, you get what you pay for. Cheap things can’t be used at all. If you want to buy them, just buy them for about 100 yuan. Of course, if you have the money, it would be best to go to the after-sales service and exchange it for an original shell worth a few hundred yuan...