Magic white stuff with Metolius's added secret drying agent. Absolutely guaranteed to make you climb even harder*!
An extra large refillable chalkball - or "chalksock" as it's referred to on the far side of the Pond (2oz = approx 55g).
NB: Some people may find the drying agent irritates their skin - we suggest not using this product if you are prone to that sort of thing.
* Maybe!