I don't think you get the Priority "Flat Rate" that RobertE was talking about unless you use the flat-rate envelope, Dave. You can use any kind of packaging for weight-rated Priority Mail as long as you use the stickers or tape you mention. The flat-rate envelope is not weight-rated; you get the 2 pound rate for whatever you can get into the envelope and seal with the self-seal flap on the envelope.

Remember too that there was a 1 pound Priority Rate implemented with the last rate increase.