The number 1 hunting bow and competition bow. The compound bow is designed to reduce the force that an archer must hold, yet increase the overall energy stored by the bow. Most compound designs use cams or elliptical wheels on the ends of the limbs to optimize the leverage exerted by the archer and to reduce the holding force of the bow at full draw in what is known as the "let-off". With less force required to hold a compound bow at full draw, the muscles take longer to fatigue, thus giving a compound archer more time to aim. A compound bow must be adjusted so that the let-off occurs at the correct draw length appropriate to the archer.