I filled it with sand and reached a weight of 22kg. The maximum weight stated, 35kg, apparently assumes a heavier filling. The inner bags are very thin and I definitely recommend wrapping them in foil or putting them in a plastic bag. One of them started to tear around the stitching. The outer bag itself seems to be durable, only the zip is not secured in any way (usually there is velcro over it). To be on the safe side, I taped it up. The strap fabric is quite rough and can scratch around the joints during explosive movements (only in certain grips). Considering the price, however, it is a good product.