i do use google before, but some say 7mm, 9mm, some say 19mm, I stop by autozone today and borrow those size and find 7mm is the best fix . thanks every one.
now my question is ( yes I did google ), about bleed the brake, some say just pump the brake pedal til it hard, and they dint say anything about open the bleed screw, now I want to make sure I need to just pump the brake or have to open the bleeding screw.