The Sibling Box is purchased as an add-on to your standard subscription and cannot be purchased individually. Add materials for a sibling to participate in every box for $15 per month! All sibling materials ship with your subscription in one box. 12 months charged upon purchase. Committing to 12 months and your subscription will renew on the 11th of the month after term. All subscriptions come with FREE SHIPPING within the United States. We ship on the first of every month.