The Vanguard Alta Stone Bag - Medium is a polyester platform that attaches to the legs of your tripod, and can be used as a counterweight when items such as stones are added, which can provide additional stability when you are using a heavy camera/lens combination, or you are operating in windy conditions where a hanging object may be blown to create movement in the tripod. It can also be used as a shelf in the field to keep essential camera accessories such as lens caps or filters safe and accessible. When used as a shelf, there a hook on the bottom of the stone bag so you can still attach additional weights The bag is made of durable polyester, and easily attaches to all tripod legs through velcro loop fasteners.Weighing less that 120g, this can be easily folded up and stored in your kit bagFeatures - Add weight in the field to provide additional stability- Use as a shelf in the field to keep essential camera accessories safe and accessible- Weighs less than 120gSpecificationsColour: BlackDimensions (L x W): b355 x 350mm laid flatFabric: 600D PolyesterSeries: AccessoryWeight: 115g