Abstract: A device, system, and method for training a user to hit a ball with a ball bat. The device and system including a main section having a light source for emitting a light energy, and an upper portion extending from the main section and configured to be received on at least a portion of a knob of the ball bat. The device may be received onto the knob, such that the light energy is generally emitted collinear with or parallel to a longitudinal axis of the ball bat. As such, a user can obtain an indication of the user's body and ball bat position. For instance, the user can hold the ball bat in a first position, projecting the light energy at a position behind the user. Further, the user can transition the ball bat to a second position, projecting of light energy in front of the user.