While wearing this belt, your Strength score changes to a score granted by the belt. If your Strength is already equal to or greater than the belt’s score, the item has no effect on you.
Six varieties of this belt exist, corresponding with and having rarity according to the six kinds of true giants. The belt of stone giant strength and the belt of frost giant strength look different, but they have the same effect.
RollQuest ships the D&D 2014 SRD as a content pack, on a 5e character sheet that does the maths - roll from the sheet and let the numbers work themselves out. Free to start.