Old-School Essentials Advanced Fantasy Reference Booklet

From the back cover:

Requires Old-School Essentials Advanced Fantasy

Quick reference for Old-School Essentials Advanced Fantasy rules and procedures:

Game procedures: Summaries of the core rules of the game, including the procedures for dungeon, wilderness, and waterborne adventuring, and combat.
Monsters: Complete dungeon encounter tables and monsters listed by Hit Dice.
Player characters: All tables pertaining to PCs, including ability score modifiers, saving throws, class skills, spell progression, and native languages.
Downtime and equipment: Common PC activities between adventures, plus full equipment lists, including mounts, dogs, and vehicles.