Vitamin D3 by Planet Source for Immune Support. Vitamin D3 Provides

What the brand says

Sold as “Planet Source - Vitamin D3 by Planet Source for Immune Support. Vitamin D3 Provides Immune Support and Promotes Healthy Bones. 1500 I.U. 100 Tablets”

Vitamin D3 is necessary for building and maintaining healthy bones. That's because calcium, the primary component of bone, can only be absorbed by your body when vitamin D is present.