Which box do I use for what service?

This topic seems to come up often in the Facebook groups I belong to, nobody can figure out which box or bag is allowed for each service. 

Well here you go.

It is a simple yes or no question , there are no grey areas. 

Now of course, you can choose to ignore this and ship out your first class label on a Flat rate priority envelope and then think you are getting away with it, that is until USPS charges your paypal account for the difference. This is something that is happening a lot. Of course, this is better than your customer getting and having to pay the difference, that makes for an unhappy customer.

Why not just do the right thing the first time?