When compared to recurve crossbows, compound crossbows may shoot arrows at substantially higher speeds. Their method allows for increased limb tension, which leads to increased velocity. Recurve crossbows are improving, but they cannot compete with the power of compound crossbows. Compound crossbows use hydraulic or pneumatic systems to cycle the bowstring and release the arrow. These devices were originally used by hunters who needed a powerful weapon for killing large animals at a distance. Today's crossbows can be found in various sizes, from small hand-held models that are perfect for hunting small game to large crossbows used by farmers and ranchers for killing large animals. Recurve crossbows work on the same principle as a rifle. They have a rotating cylinder called a crankshaft that is attached to the end of the handle opposite the aiming point. This crankshaft houses the mechanism that cycles the bowstring and releases the arrow. A recurve crossbow can only fire one arrow at a time. This limitation is not a problem for most users because they will always have one target that needs shooting! Compound crossbows can hold more than one arrow and are best used when you want to kill several targets simultaneously. They are commonly seen by hunters trying out different types of game. Recurve crossbows were initially developed in Europe around 1550.