We took advantage of the high quality materials to make sure the quality is excellent. The heavy duty workout sandbags are made of canvas, strong and durable, would hold up to years of use.The Canvas-Kettlebell-Sandbag has an ergonomic handle with silica gel grips for comfort.No Sand Leakage: The training sandbag has a sturdy buckle to ensure filler material stays fully contained as you work through your regimen, no dirty clothes. Weights from 0 to 22 pounds, depending on the material used to fill the bag. You can easily adjust the weight you fell comfortable with. The filling material can be sand, soybean, iron powder and rice. Sandbags can be emptied and then re-filled, they function as uniquely portable strongman training tools for athletes of any experience level.