From the instruction sheet:
The Random Encounters Dice System for all Role-Playing Games
Roll all five dice at the same time. The multi-colored dice (selection die) with the three different shapes, determines which of the monster dice you use. The green circle means to use the green die (easy monsters). The orange triangle means to use use the orange die (medium monsters). And the red square means to use the red die (tough monsters). Finally, the die with the faces on it determines the monster's initial reaction to the party (Reaction Die).
Five six-sided dice and a folded instruction sheet, inside a plastic tube. The Reaction Die was also sold separately. This dice set was published by Flying Buffalo Games.