A sandbag can serve as a useful platform for shooting a sniper rifle, although any soft surface such as a rucksack will steady a rifle and contribute to consistency. In particular, bipods help when firing from a prone position, and enable the firing position to be sustained for an extended period of time. Many police and military sniper rifles come equipped with an adjustable bipod. Makeshift bipods known as shooting sticks can be constructed from items such as tree branches or ski poles. Some military snipers use three-legged shooting sticks.