As the gymnast increases the difficulty of their skills they should also continue developing their air sense to know where they are during many different skills. Another important thing to learn is to bail out safely when making a mistake that causes them to fall off the equipment.
A low single rail is a very useful piece of equipment to master different technical aspects of several horizontal bar or uneven bar skills. The back bail is the beginning part of back giants. The drill is performed falling very stretched from the handstand and landing flat down on soft mats approximately at the same height as the low rail.
In the front bail drill to prepare the first part of the front giants the gymnasts bail down with the shoulders very stretched and the body straight aiming to land on the mat as flat as possible without any hips pike or shoulder angle.