B00GWSB2II Oncourt Offcourt Serving Sock – Improve Rhythm and Fluidity of Serves/Correct Uneven and Awkward Serving Motions

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EASY TO USE: Simply swing the Serving Sock like a racquet and avoid hitting your back.
SIZE: Same length as a tennis racquet from grip to center of strings.
IMPROVE: The Serving Sock helps your serve in various ways: rhythm and fluidity and by correcting awkward serving motions.
FITS ALL: The Serving Sock can be used by beginners and experienced players. Try tossing a ball and hitting it with the sock as an advanced drill.