these are a great option for hikers as they tick all the boxes and are versatile, durable, do not puncture, are not noisy, and are affordable
they are warmer than an un-insulated air pad
can be used outside the tent to sit on or as a knee pad without worrying about puncturing it
they are generally carried by strapping to rear of the back pack
they can be used on stretchers or under air mats to provide added insulation and comfort
closed cell foam refers to how the air pockets in the foam are not interconnected, resulting in a foam that is generally denser, waterproof, more insulative, more resistant to damage, and fairly stiff and uncompressible.
in contrast, open cell foam has air pockets that are interconnected, resulting in a spongier foam that is generally less dense, less insulative, will absorb water or allow it to pass right through, and is usually relatively easy to damage. It is often used in the self-inflating mats
aluminium coating layer adds ~15% more warmth and in winter, ideally should be placed upwards to reflect your body heat back to you (most companies state it should be down but this is probably for durability and for warm nights)
the thicker the mattress, the warmer and more comfy it will be but also more bulky and heavy
ideally they should be 65cm wide for comfort but this makes them heavier and longer to carry so most designed for hikers are narrower than this
come as either roll up mats or foldable mats
modern closed cell hiking mats are made from either XPE or IXPE foam which are much better than older polyvinyl chloride/nitrile rubber (PVC/NBR or Ensolite) but these deteriorate in UV light hence are no longer used for hiking
XPE foam
cross-linking of PE is via a chemical process and results in a more larger, rougher foam
these can be bought from Temu starting at around $20 but are of inferior quality/design to more expensive ones at ~$40
IXPE foam
EVA
Evazote
examples with aluminium backing: