Abstract: A trainer assembly for teaching effective baseball and softball batting technique includes a sleeve having an interior bat chamber adapted to house a barrel of a baseball bat and having a single open end terminating in a guide, and a retractable arm affixed to a closed end of the sleeve that is length adjustable and rotatable within an attached elbow, allowing a range of angle adjustment for positioning the sleeve. The elbow is 360 degrees rotatably affixed to a support at one end and at an opposite end holds the retractable arm at a fixed 45 degree angle below a horizontal plane measured from a top of the elbow. The elbow's horizontal rotation can be optionally locked. In an improved embodiment, the support is height adjustable via telescoping shaft portions. A method for using the trainer assembly is included.