The best part is if you're shipping in your own Box or a Priority Mail Mailing Box and the package is small enough, you can qualify for a Cubic Pricing Discount which is only applied to packages shipped out via Priority Mail.
Just some quick little notes:
Packages Can't Exceed 70lbs
Personal Boxes Can't Exceed Length + Girth of 108"
Priority Mail usually arrives within 1 - 3 days, but this is not guaranteed.
Did you know that the Post Office gives away Priority Mail boxes for free that even qualify for Cubic Pricing? Check out their Store for FREE Supplies!