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Sounds like it.
https://www.terra-nova.co.uk/tarps-bivis-bothies/all-bivis-bivi-bags/moonlite-bag-cover/
The Moonlite bag cover is an asset to our award-winning range of bivi bags. This waterproof and breathable bivi has been updated in 2014 and now has a mesh upper section with zip closure at the head. Along with a draw cord closure at the entry, it is fully seam sealed making it the minimalist's perfect choice to couple with a tarp. The Moonlite's tiny pack size and weight also means it can double up as a survival bag on longer trips. Used with the new mini tarps it makes a great sleeping system.
Minimum Weight: 0.21Kg (0lb 7oz)
Packed Weight: 0.21Kg (0lb 7oz)Superlite sleeping bag cover which can double as an emergency bivi
Waterproof and breathable with taped seams
Zipped hood
Size: 200cm x 76cm
Packed Size: 21 x 6 cm
Protect your down bag from moisture to stay warm and dry
I wonder if that is actually waterproof, seems to cheap/light to be true.