We're working out what we think - we'll add our view here!
Mountain Equipment says:
Warm and packable hut slippers with a tough, slip resistant sole. Combining POLARLOFT® Featherless synthetic insulation and a Helium™ 20D outer shell, Superflux Hut Slippers are warm, light and highly packable. With a tough, slip resistant sole and comfortable brushed lining they’re perfect for life in high mountain huts.
Material & Construction