Since 2nd or 3rd Quarter the USPS classifies bubble pack mailers as parcels. Previously if the were envelope sized, fairly uniform in thickness and up to 1/4 inch thick they were classified as large envelopes. First Class Parcel Post under 4 oz is $1.95 USD, although the rate will go up in January. First Class postage for large envelopes up to 1 oz is $0.90, again subject to increase.