The sandbag is empty, can put things like a rag, sawdust, sand, beans in it. After padding, the sandbag can absorb shock to decrease the impacts and protect your bones.Good quality oxford cloth material is wear-resistant and durable for years of use, with PU patch on the middle which is sleek enough to protect your hand from abrasion. The stitching is solid and delicate, you don't need to worry it would split or tear. Metal buckles can firmly connect the sandbag and metal chain. Zipper seal, convenient and safe. The metal chain is sturdy and heavy-duty, you can hang it a wall or other items. Perfect for developing hand and foot technique and building nice body.