When stringing, the machine continuously displays the force on the display and stops when reaching the set kg. As the machine is a table model, the machine can be easily transported into a car to participate in a tournament, for example. It continuously measures the force on the string and balances it lower or higher. Automatic Tennis & Badminton Stringing Machine Machine is black, self-calibrating and includes an extensive tool set When tensioning to 25 kg, for example, the machine tensions only a little more (you can choose 10/15/20/25% extra) and then returns to the set kg. You can set how much extra kg you want by pressing the knot button. The number of kg always corresponds to the correct kg. Pre stretch - The machine has a pre-stretch, which is very important for stringing with the right force. Self-calibrating - The device is self-calibrating. Upgrade your tennis game with top-notch stringing machines like Silent Partner Electronic and Prince 7000. Shop now on for the best deals As the machine continuously measures and displays the force on the string, it does not need to be calibrated. String Machine Band Protennis RHAPSO Professional Linear Electronic Stringing Machine Constant Pull Racquet Stringer