Yes, you get a lower postal rate if you send your chip in an envelope and make it look like a letter. However, the reason letters get a lower rate is that they are handled by high-speed machines that accelerate and stop the letters suddenly and take the mail around corners. You want your chip in a package that looks like a package and won't go into the letter stream. Bubble pack envelopes work fine for this.

Pay the extra pennies and get your chips there in one piece .