Keep your reference tension in check with the tension calibrator stringing tools. A must-have for proper stringing machine maintenance. After a racket has been strung or used over time, the midpoint tension reading on the gauge may be lower than expected, while tension values around the edges tend to be higher. Compared to the horizontal strings, the vertical strings often show higher tension readings. Specifications: - 0-42 lbs - Helps determine when it is time to restring - Easy to operate - Model: AC-SM200 - Color: Black - Material: PVC Package Contents: 1 x Tension Calibrator Note: Light shooting and different displays may cause the color of the item in the picture to vary slightly from the real thing. Measurement error allowance is +/- 1-3 cm.