How do self-inflating camping mats work?

Self-inflating camping mats use compressible foam insulation and inflate like an airbed without requiring the use of an air pump. They are warmer than airbeds, and more packable than simple foam camping mats. They provide a comfortable and portable sleeping surface that can be carried with ease during camping, hiking, or other outdoor activities. It sounds like magic, but there

Halfords Self inflating Mattress - Double

【Extra long & 5 Thick Sleep Support】The self inflating sleeping mat for camping is up to 81*26*5 inches after inflation, bringing you extra thickness

WILSNEY Camping Sleeping Pad, 5 Inch Ultra Thick Self-Inflating Sleeping Mats with Pillow and Built-in Foot Pump, Compact & Lightweight Camping Mat

TETON Sports ComfortLite™ Regular Self-Inflating Sleeping Pad with Velcro

Dozer Self-Inflating Camping Mattress

Camping Mat Buying Guide - Trail Outdoor Leisure

How Does a Self-Inflating Sleeping Pad / Mat Work? We Have the Answers!

How to Inflate a Self Inflating Mattress - Outdoor World Direct

Self-Inflating Sleeping Pad with Pillow

Swiss Gear Self Inflating Mat Reviews - Trailspace

Self Inflating Mattress - Outwell Self Inflating Air Camping Mat

3 in. UltraThick Self Inflating Memory Foam Camping Sleeping Pad, Blue SMG-03 - The Home Depot

KingCamp Self Inflating Camping Mat Double 7.5cm / 3 in - Foam Sleepin –

Sleeping pad - Wikipedia

How Does a Self-Inflating Sleeping Pad / Mat Work? We Have the Answers!