Abstract: A baseball bat swing trainer attaches to a baseball bat and is configured to train a batter to maintain a level swing. The baseball bat swing trainer is attachable to a horizontal structure that is over the head of the batter and to a baseball bat. The baseball bat swing trainer includes a single-unit line controller, a line, and a baseball bat coupling connected to the line. The line controller is configured to vary and fix a working length of line defined as extending from the line controller to the baseball bat. The line may be varied in length, a working length, in order to accommodate different size batters. The line controller is configured to keep and release excess line. The coupling is secured onto the baseball bat at a location taken from a handle of the baseball bat that is approximately 50% of an overall length of the baseball bat.

Abstract: A baseball bat swing trainer attaches to a baseball bat and is configured to train a batter to maintain a level swing. During training swings, the baseball bat is constrained by the baseball bat swing trainer so as to not allow the baseball bat to go below a level swing for a particular batter. The baseball bat swing trainer is attachable to a horizontal structure that is over the head of the batter and to a baseball bat. The baseball bat swing trainer includes a single-unit line controller, a line, and a baseball bat coupling connected to the line. The line controller is configured to vary and fix a working length of line defined as extending from the line controller to the baseball bat. The line may be varied in length, a working length, in order to accommodate different size batters. The line controller is configured to keep and release excess line.