Do I have to send item in envelope to get the letter rate?

[super-simple-life]

Hi,

I just start selling small item on ebay. I know the item need to be less than 20mm thickness to be ship as a letter to get the letter rate ($1-3), which is much cheaper than ship as a satchel rate ($7 +). Do I have to send item in envelope to get the letter rate?

For packaging, I found it much easier for me to put my good into satchel. And I can also get satchel which cheaper than envelope. Therefore I want to know, Can I pack my good in satchel, but keep it small, so the thickness is less than 20mm? Can I just pay letter rate for that?

Or the people in the post office or whoever handling it will just look at it and say it is a satchel, so I have to pay the satchel rate.

I hope there is someone can help or have done similar thing before, can tell us more information about it. 

Thanks

[super-simple-life]

I can get them very cheap from the Manufacturer too. it is so good to know I can just use satchels. because they are much tougher than envelop and rain proof.

[lowanacrafts]

These little boxes are great. I use them all the time.