We ship exclusively via UPS and USPS, which carrier depends on the products purchased. Orders of 1000 bracelets or less or 200 glow sticks or less will ship USPS so using a P.O. box is ok. Anything larger (including any necklaces) will almost always ship via UPS and we will need a physical address to ship to.  If you have any questions about delivery please email us and Be sure to include your zip code and what you intend to order and we will be happy to give you an estimated delivery time. Please note, delivery estimates are based off of information provied to us by USPS/UPS and are not guaranteed.