Pied d’Elephant - or Elephant’s Foot - is a down bivi bag designed to be used with a down jacket (and sensibly a Gortex bivi bag) on an lightweight bivouac or alpine camp. Nearly the same level of comfort/insulation as sleeping bag for much lower weight penalty.
As Alpkit describe it: Reduce weight and bulk in your sack. This Pied d'Elephant style sleeping bag is only insulated from the waist down. The upper section is a lightweight waistcoat cum braces arrangement to mate the bag with your down jacket. We originally designed the bag with lightweight alpinists in mind; striving to shave a few grams when they’re pushing their limits.
If you’ve got a big jacket for sitting in, you don’t necessarily need a big bag for sleeping in. This is a half bag and if it's half a bag then it's half the weight. The rationale being if it is half the weight we can all climb, bike and hike that little bit better.
Has a 200g full weight (equivalent to 400 g fill on a standard length).
Has only been slept/bive’d twice - in dry, but cold conditions so is essentially new. They do work and I’d had comfortable nights!
When not being carried in my rucksack it has been properly stored in a dry and aired cupboard so still has full loft and insulation. Has mesh storage, but I can’t find stuff sac (easily/cheaply replaced).