Sleeping pad

In camping, a sleeping pad is a simple device often used in conjunction with a sleeping bag. Its purpose is to provide padding and heat insulation. The ground may become quite cold at night, and is often covered with sticks[?], small rocks, and other objects that may make sleep difficult. A sleeping bag does not provide adequate protection against either hazard, but a sleeping pad does.

The simplest sleeping pads are sheets of firm plastic foam[?], stored in a rolled-up configuration. More expensive (also heavier) models are designed with interconnected air cells that may be compressed for maximum compactness, or inflated through a valve for maximum padding.