Question Can someone tell me what battery would fit Asus x555u model?

[gordmathison]

part numbers for laptop batteries

 

[punkncat]

Of the assumption that you don't have the battery I would suggest your looking up the manufacturer website and see.
If you do have the old battery, the part number will be right on it somewhere.

Don't buy budget solution battery if you are planning to keep for any amount of time.