lake What is a ups drop box?

What is it, how do I use one, I need to ship mouthpieces I ordered back to a company and need to know how to do all that stuff, do I use a drop box? Do I just bring it to a normal ups store? Or can I just bring them to my local post office and feel safe, remember this is like some expensive stuff, lomax and vandoren mouthpieces. PLEASE I NEED TO KNOW HOW TO DO THIS CRAP IM JUST SOME KID. Well my parents are gonna help I just want to be ahead of the game. Thanksthere