Define
The core offer is surrounded by named extras so the package feels uneven in the buyer's favor.
Mechanism
Accumulation. Each add-on is priced in the mind, then included. Distinct from a guarantee stack: this adds value, that removes risk.
Verdict
The extras are real and wanted. The stack should survive a skeptical what do I actually get.
Don't
The bonuses are filler PDFs. A stack of nothing trains the buyer to discount us.
Rights-cleared examples
Just send 10 cents to Reader's Digest" condensed books club ad, Modern Screen September 1958