At rank 3, the power of your portfolio keeper becomes more potent, making it a rare magic item. When you give out a business card stored in your portfolio keeper, you can choose to have the card allow its recipient to contact you through your sending stone as if they had cast a sending spell. A business card loses this power seven days after it has been given out, and no more than five cards can have this power at one time.
You can also use your sending stone to cast sending and contact anyone who has one of your business cards. Once you use this feature of the stone, you cannot use it again until dawn seven days later.