The Lifesystems Thermal Blanket is a single-use emergency foil sheet made from metallised polyester, sized at 210 x 140 cm and weighing 55 g. Wrapped around a person, it's rated to reflect up to 90% of body heat back, making it a standard piece of kit for treating or preventing hypothermia after an injury, a sudden weather change, or while waiting for help. The outer surface is orange rather than plain silver, which doubles as a visual signal for search and rescue - a small but genuinely useful detail when visibility matters more than the marginal weight difference.
It's recommended kit under the Duke of Edinburgh's Award scheme, reflecting its status as a baseline first-aid item for hiking, trail running and general mountain use rather than anything specialised. Being single-use and foil-thin, it has no structural durability and won't survive repeated packing and unpacking, so it's best treated as an emergency-only item rather than a regular shelter layer - carry it, hope not to need it, replace it once used.