One of Kristoff's possessions is a lute.
While traveling to the North Mountain, Anna used the lute as a makeshift weapon to defend Kristoff's sled from an attacking wolf. The lute was ultimately lost when Anna, Sven, and Kristoff were forced to abandon the sled upon encountering a gorge, though the princess promised to replace everything lost. True to her word, Anna gave Kristoff a new lute along with his new sled.
During Christmas, Kristoff played his new lute as he sang his tradition to Anna and Elsa in hopes of cheering them up after the citizens had departed.