Check the listing for details. Gym Chalk Block for Gymnastics Weight Lifting Rock Climbing Crossfit [1,2,4,6,8]. Color: White, Condition: New. Listed at 8.49 USD. Best climbing chalk made with 100% magnesium carbonate to ensure moisture absorption and prevent hand cracking.Chalk blocks multiple packages available of 2, 4, 6, and 8.Each block is 2 ounces What is gym chalk, gym chalk block, or what is it made out of?Gym Chalk is magnesium carbonate Chalk and helps to secure a proper grip by soaking up the moisture on your palms and fingers. While some people like to use weight lifting gloves, the best way to a firm grip is by using chalk which is the reason why gymnasts and power lifters use chalk What is gym chalk used for?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, are an inexpensive but professional quality chalk block. It can be carry in a gym chalk bag for training at the gym, outdoors, or any sports event.