If the ball is set for the attack by hitting the ball in the air and allowing for a bounce, this is called an indirect set. The setter has to calculate the trajectory of the hit so that the bounce is at its highest point approximately 2.5 - 3.0 m in height, as this is the most effective height for an attacker to jump and strike the ball over the net. The field conditions, distance to the net and possibly the wind direction all have to be taken into account when performing the set. In addition, the ball should ideally have some forward spin so that the attacker can use this forward momentum in his or her attacking hit.