Z-Athletic Athletic Chalk Block 1lb of eight 2oz Chalk Blocks 100% pure magnesium carbonate chalk block made to greatly improve grip for gymnastics, rock climbing, bouldering, weight lifting, and so much more Used in gyms across the Globe, Z Athletic chalk balls are an inexpensive but professional quality chalk ball. Made with 100% magnesium carbonate to ensure moisture Absorption but prevent caking Check out our Z Athletic chalk ball bags for a mess-free workout