Our 3-Day Select service was designed to give your order priority and also makes sure that it ships the same day you ordered and that it arrives on the 3rd business day. We use several different shipping methods to accomplish this priority, so this does not always mean that the shipping method used will be any specific service. Sometimes the item will be shipped ground, 3-day or sometimes 2nd day or next day air in rare cases.
Of course, always make sure to check the availability status on the product to get an idea of how quickly your items will ship. Most items ship the same day but some items require a few days of lead time.