Beautiful seam, and spiral reinforcement adopted, preventing the burst in boxing. Empty sandbag and zipper seal, easily to adjust the weight of the bag when filling. You can DIY! Three bolts on each side to reinforce, good drapability and stability with strong weight bearing capacity. Made of durable oxford cloth, and well welded chains, greatly ensuring the safety of sandbag after . A great workout tool for stress relief, self-protection, enhancement and sensitivity and responsiveness improvement.