The Therm-a-Rest SOLite (part of the RidgeRest line) is a classic closed-cell foam pad made from IXPE foam, with a reflective ThermaCapture coating that bounces body heat back toward you and boosts insulation without adding foam thickness. That brings the R-value up to 2.1, a step above a plain foam pad of similar weight and dimensions.
The textured, dimpled surface reduces ground contact and helps with both insulation and comfort compared to a smooth-faced foam pad. Unfolded, it measures 183 × 51 cm at 1.5 cm thick; folded down it packs to roughly 51 × 20 cm, with no stuff sack — it straps to the outside of a pack instead.
At 400 g and with no valves, chambers, or anything that can fail, the SOLite is close to indestructible and carries zero risk of a mid-trip puncture — a solid choice as a rugged standalone pad or as a protective underlayer for a pricier inflatable. The trade-off, as with any foam pad, is less sleeping comfort than an air pad delivers.