A super comfortable, durable closed-cell foam mat with accordion-folds to make it easy to pack up and lay out. This is a great option for a standalone sleeping mat or as an additional layer beneath your inflatable mat to add warmth and prevent punctures.
Although some may argue foam pads are less comfortable than inflatables, the price, durability (don't have to worry about it popping!), ease of use (no fuss trying to inflate it!), and adaptability (I have used this thing as a sit pad, a sleeping pad, a mosquito shield, an umbrella, and a wind shield) makes owning a foam pad a no brainer in my book. I have previously used the Nemo Switchback (used it on my whole PCT thruhike) and the Thermarest z-lite and so far found this one to be significantly more comfortable and slightly warmer than either of the other two. The biggest factor in a sleeping pad for me is durability--I don't want to have to keep replacing my pad every summer. In my experience the switchback compressed very quickly, but it still lasted me 2,200 miles so no complaints. The Thermarest definitely stands the durability test as numerous of my friends have had theirs for years and theirs haven't compressed as much as my switchback. I have only used the exped for ~6 nights so far and it seems to be holding up well! I am hopeful it lasts awhile, but only time can tell!