From the back cover:
Welcome to Spinward Encounters, a series of short adventures and adventure seeds for Traveller from Avenger Enterprises. This book is intended to be used with the Traveller roleplaying game from Mongoose Publishing. Other versions of the Traveller game, and indeed entirely different rules sets, can be used with this adventure with only a minimum of effort, but the contents of this book are specifically designed to be compatible with Mongoose Traveller and with the 'Spinward Marches' background published to accompany those rules.
With a variety of patrons and 16 full-blown adventures set in Amber Zones throughout the Spinward Marches, this book contains enough to keep your campaign going for many, many months in a variety of the Marches most exciting locations.
Spinward Encountered is set in the Spinward Marches sector of the Third Imperium, part of the Official Traveller Universe (OTU) and requires only the Traveller rules to play. However, additional materials may be useful. In particular the Spinward Marches Sourcebook from Mongoose Publishing presents details of the surrounding area and will add greatly to the gaming experience. Other Mongoose Traveller books and supplements may be of use tot he Referee.
To use this supplement, a Referee will require the Traveller Core Rulebook.