From publisher blurb:
While many other Djorde books are descriptive of the setting, this book instead provides supplemental rules (compatible with 5e and potentially other systems as well) that you may use in your own campaign. These rule supplements are primarily written for Gamemasters (GMs), but with your GM's permission, players may read them, too. Each of these supplements are meant to expand the stories you can tell within the Djorde setting, providing mechanical rules to guide Djorde's novel themes.
This book contains equipment and objects suitable for a campaign in modern-day Djorde, including firearms, vehicles, electricity, survival supplies, magic items, and measurement tools. You may also find that these items are useful for gilded-age campaigns in other settings, as well.