He has a second costly thing, best of all: the girdle of might; and when he clasps it about him, then the godlike strength within him is increased by half.
In Snorri Sturluson's retelling in Skáldskaparmál of Thor's visit to the court of Geirröðr, Thor had not his hammer with him, nor his girdle of might, nor his iron gauntlets, which was Loki's doing. He came to spend the night with the giantess Gríðr, the mother of Víðarr, who warned him Geirröðr. She then lent him her own megingjörð, as well as a pair of iron gauntlets and her staff Gríðarvölr.
A kenning for Thor is Wielder and Possessor of Mjöllnir and of the Girdle of Strength.
- Gylfaginning, 21, 45.
- Skáldskaparmál, 4, 18, 49.