Pre-strung and recommended
Factory tension: 8-10 kg.
Tension recommended by the brand: 8-13 kg.
The rackets come with a tension that ranges between 8 kg and 10 kg, depending on tension losses that occur during transport. Each brand indicates a recommended tension, generally somewhere between 8 kg and 12 kg. This is to prevent the string or frame from breaking while stringing or hitting. Finally, some rackets have a reinforced frame that can withstand a tension of up to 16 kg.