The most important thing
Grades describe cosmetic condition, not functionality. All iPhones function at 100% regardless of grade.
ZonaPhone Grading
Satisfactory: visible signs of use. Most economical option. Premium: flawless, practically like new.
Which one to choose?
Premium if appearance matters or you use without a case. Satisfactory if you're going to use a case or budget is a priority.
What does NOT change with the grade?
Identical functionality, same 2-year warranty, same 14-day return policy, same technical inspection.