Falconry training and technique two parts that twist freely, each with a metal hoop on the end. The swivel may be traditional, or modified. The modified swivel has much larger metal hoops than the traditional. While swivels have been made of cloth or other materials in the past, most modern falconers use metal swivels. See Falconer's knot for more information about tying off the bird to the glove. When using Aylmeri jesses, there are usually two sets of straps: the mews straps, for manning and tethering the bird, and flying straps. The flying straps are lighter and smaller for hunting; the mews straps are
Leather cannon especially if the terrain was uneven. Gustavus Adolphus' tactics were based on use of effective firepower. While heavy cannon were effective at the start of the battle, they could not be moved from the hill that they usually were deployed on (the guns themselves weighed from roughly 300 kilograms (660 pounds) to 3 tons). As such, the artillery could not respond effectively to developments in battle. In order to fill the gap, the so-called "leather cannon" was developed. A relatively thin copper tube was reinforced by heavy cords and finally clad in leather (alternatively clad in leather straps first and