Caldwell Tack Driver X Bag Rest - Green - The Tack Driver X Bag is the perfect bag for getting a stable shooting position no matter what the situation. With a unique design, the Tack Driver X is ideal for PRS match use on barricades, rooftops, window and port openings or any other surface. The versatile design also works well for sighting in on a bench and hunting in the field. An adjustable strap allows for height adjustment and acts as a carry handle. A rubberized bottom material prevents sliding for a stable shooting position.