Up to 4. Every item page has the same field in its sidebar.

Stat	Copper Round Shield+3 D1Chinese × Change Plus0123456789101112
Melee Defense Power	4
Magical Defense Power	6
Melee Specialization(%)	4.4
Magical Specialization(%)	7.4
Blocking Rate	10
Durability	47

Orange is the higher stat, ranked by the middle of the pair ((min + max) / 2): 23~28 against 20~34 has no answer without a rule. The faint number is how far that column sits behind. Values are what the item has empty. A dash means the item has no such stat at all — not that it has zero.

Nothing here is ranked: a lower required level is an advantage to one player and a different item to another.