Media Mail is a less expensive shipping option and the USPS now includes tracking with media mail, so at least if your product goes missing, it can often be located.
However, Media Mail does not include insurance against damage or loss--without insurance, we cannot replace your items if they are lost or damaged in shipment.
Additionally, Media Mail is less focused on timely delivery, which means that your products could be delivered later than you might expect, delaying your plans for using them.
COVID-19 Update: Customers reported delays in all forms of shipping, with Media Mail facing the most extended delays because the USPS "demotes" this in its priority list.
All shippers (FedEx, UPS, USPS) report longer-than-usual delivery times due to the increase in online shopping. All of them provide tracking numbers so you can know when to expect delivery of your order.