Sand Disc, has handy grips around the entire rim for better control. Use them just as you would a medicine ball, except now you can stack multiple for an extra challenge (and easily stack them when not in use). Made with durable for high-impact training, this weighted disc is the toughest and only reinforced disc on the market, and lets you break a sweat with every move in a size that fits easily in a travel bag. Filled with soft steel sand to maintain its shape and reduce shifting.