From the publisher's website:
fantastic spoils of the Council of Thieves Adventure Path take form in this new assortment of 54 unique GameMastery Item Cards. From specialized thieves tools to the diabolical sacrificial daggers and devil-faced platemail of the Hellknights of Cheliax, the idea-inspiring items in this set add an underhanded dimension to any Item Card collection and bring a great sense of immersion to Council of Thieves campaigns, or any fantasy campaign!
GameMastery Item Cards allow heroes to keep track of their equipment in style, and the set is completely compatible with all of Paizo's other GameMastery Item Card sets. Each of these full-color cards features a beautiful portrait of an item on one side with space on the back to keep notes. GameMastery Item Cards are compatible with any fantasy roleplaying game.