In Andersen's fairy tale Wild Swan, what did my sister weave to save my brother?

In Wild Swan, my sister knitted a cloak to save my brother.

Princess Elsa's brothers were turned into ten wild swans by magic. During the day, they will lose their human form and become swans, and at night they will become human again. Only when a pure girl hugs them can they return to their original shape. Elsa was sad for five days and didn't eat or drink. She told all that she had done for her brothers and even knitted cloaks for them, but she was afraid to touch them herself. This made her brothers recover quickly.

Therefore, it was the cloak that saved her brothers.