Beginning about 1998 The American Lung Association started mailing their Christmas and Spring issue Seals in large colorful flat packs, and shifted almost exclusively to self adhesive, away from re-moist (lick and stick) gum. Though self adhesive gum had been used by them since the late 80's, it had become the preferable means to affix a Christmas Seal.
These flat packs contained a variety of bonus items. Of greatest interest to collectors were the Christmas and Spring issue Seals, and the Special Occasion Sheets. A Special Occasion sheet consists of free form (die cut) stickers (which have elements of Seal designs) as well an attached calendar or personalized return address labels.
Also included in packets were Gift Tag only sheets, Holiday Gift Packs (containing note paper as well as "to and from" gift tag and free form sticker sheets), calendars, punch out ornaments, a self adhesive picture frame, a pendant, certificates of appreciation, fundraising letters, note paper booklets, return envelopes, etc.
Betsy & Chuck Berry began work on these modern "Back of the Book" ALA issues, listing items deemed to be outside the scope of Green's Catalog (Calendars, Ornaments, postcards etc.). Their work is included in a separate chapter in Green's Part 1, US Christmas Seals, CD only.