Except for orders of small items, most of the products we ship are mailed via USPS Media Mail. This is a space available mail which works well most of the year and helps us keep shipping costs to a minimum. However, when mail volumes increase, as will happen around the Christmas holidays, Media Mail can often be delayed. If you are ordering items that are time sensitive, please call us at 303-456-4564 to make sure that the items are in stock and that we select the best shipping options for your needs.