A product that comes bundled with another product, in the same box.
1977, Richard Adler, Research on the effects of television advertising on children:
The prohibition would include offers of "pack-ins" (small toys or other objects included in the package), "pack-ons" (cut-outs on the side of a cereal box), reusable containers, self-liquidating premiums, and any kind of remuneration for purchase, including free gifts.
1984, Marketing & Media Decisions, volume 19, page 130:
This segment of sales promotion - premiums and incentives — also includes use of contests such as Benson & Hedges' 100 Sweepstakes, as well as factory pack-ins.
1988, Allan J. Magrath, Market smarts: proven strategies to outfox and outflank your competition:
Not all promotions simply reward trade channels with free goods, extra discounts off invoice, extra pack-ins, and so forth.
1997, Boot, volume 2, page 65:
Software pack-ins include Virgin's The Daedalus Encounter, Tsunami's Silent Steel, Activision's Muppet Treasure Island and Spycraft, Origin's Wing Commander IV, and Xiphius' Encyclopedia Electronica.
2013, Sam Pettus, Service Games: The Rise and Fall of SEGA: Enhanced Edition:
By 1994, gamers had come to expect that each new system would include one or more games in the package. "Pack-ins" enabled buyers to immediately enjoy a game specifically coded to deliver an experience that only their newly acquired hardware could deliver.