Sandbags are used whenever you need extra weight to prevent tipping. You usually "bag" stands, especially when the weight is off center, such as with a heavy Scrim. They help stabilize equipment in windy situations and can counter balance Boom Arm applications.
The empty bags are completely sewn except for a 1" seam, left open for the user to fill and then sew closed. This can save on the shipping charges, however, the user will require a heavy duty machine to sew the sandbag closed properly. The Matthbags and the Fly-A-Way bags are a must for the traveling photographer. The bags come empty, and can be filled on site with rocks, gravel, or whatever. The Fly-A-Way has a Velcro strip to seal it and the Matthbag has 4 zippers.