This is a black, 30 lb capacity Tenba Large Heavy Bag.
A sandbag constructed like a saddle bag. The two pockets can be filled to provide weight and used to hold down light stands, cables and other objects. The pockets use two zippers each, which open in opposing directions. This eliminates the nuisance of leaking sand. The handstrap on top opens with a side release buckle.
Tenba Large Heavy Bag (30 lb, Black)