A bag of clay pebbles for plants ~40L (islington N1)
Exactly like here: https://www.amazon.co.uk/Hydrogarden-Canna-AquaClay-Bag-45L/dp/B003Y7M6B2/. Bought a large bag by mistake, only needed a few liters, so ~40L are left in the bag.
This offer has been gifted to someone and is no longer available.