In camping, floor pads, sleeping pads, thermal pads, sleeping mats or roll mats are lightweight mats that are common among hikers, backpackers and budget travellers and are often used in conjunction with sleeping bags. Their purpose is to provide padding and insulation. All types currently available use air as their primary form of insulation.
In their simplest form, sleeping pads consist of a foam-like material about half a centimetre thick (about a quarter of an inch). The size of the pad is usually roughly the same length as the sleeping bag, but slightly wider. Subtle variations in design can be found, such as corrugations in the foam, but these do not significantly affect the pad's thermal performance.
The main purpose of the pad is to prevent the body from dissipating heat to the ground while sleeping. The material used is usually filled with air pockets that slow down the heat transfer through the mat, as air is one of the best (and cheapest) insulators. The air pockets also serve to cushion the body from any rocks or other objects that might be underneath.
There are a number of ways to inflate sleeping pads, the most common being via a small built-in foot pump, or by mouth. Some models have a valve that can be opened to allow air to flow in, and then closed to trap the air inside. Inflating by mouth can be tiring, and may introduce moisture into the pad.