This is a slip case containing the Player's Guide, Gamemaster's Guide and Bestiary for Ruins of Symbaroum.
From the back of the books:
With the Ruins of Symbaroum game line, the acclaimed setting of Symbaroum comes to the world's most popular roleplaying game rules! This gamemaster's screen and adventure booklet will serve you and your friends well when you start exploring the game world, using the 5th Edition OGL ruleset!
The Ruins of Symbaroum Gamemaster's Screen provides easy access to important tables and information from the Player's Guide, Gamemaster's Guide and the 5th Edition OGL ruleset, including Marks of Corruption, Enemies in Davokar and a listing of various Conditions. The screen comes with a 29 page booklet featuring two adventures Where Darkness Dwells and The Gathering Storm, suitable for player characters of levels 2 to 4.