Rock sacks are simply sacks of rocks. They're most often utilized by Abe as tools for clearing paths.
Rock sacks can be found dangling from ceilings more commonly in nature sections rather than industrial sections. If the player were to jump underneath them a rock would fall out. If the player were to then crouch on the rock Abe will receive some rocks. Abe can, at times gain more than one rock per rock sack. The amount of rocks Abe has is represented by a green number that appears when picking up rocks and right before Abe throws one. Rocks are most commonly used for clearing hazards that impede Abe such as Land Mines and UXBs. The rocks can be thrown in one of four directions being up, down, left, and right.