The HamiltonBuhl SOP-SC-7V Sack-O-Phones - 5 Pack of Hamilton SC-7V Deluxe Headphones with Leatherette Ear Cushions and Volume Control. Sack-O-Phones packaging is a unique bag that doubles as a knap sack and holds 5 deluxe or 10 personal headphones. It's a great way to store headphones easily and economically, no need for costly plastic cases for storage.