I don't see how poly bags offer any weight advantage over an envelope. The advantage they have is durability: paper envelopes get easily ripped open, whereas p

I don't see how poly bags offer any weight advantage over an envelope. The advantage they have is durability: paper envelopes get easily ripped open, whereas poly bags are nearly indestructible for about the same weight and size. I've also noticed that many shippers now print their mailing/customs label directly onto the poly bags, so that probably makes the shipping process faster and more automated.