PETZL - Power Crunch, Chalk Pack for Climbers GET A GRIP: The POWER CRUNCH chalk improves your grip on rock or gym holds. DUST-FREE: The bag includes a mix of chalk powder and larger chunks of chalk to reduce dust. SIZE OPTIONS: The POWER CRUNCH comes in two sizes: 100 grams, which fills one chalk bag and leaves a little extra, and 200 grams, which can be stored for refills. SAVE FOR LATER: Fill up your bag now and save a little for later. Both size bags are fully resealable. MATERIAL: The chalk consists of 100% magnesium carbonate.