Description:
It accelerates the formation of muscle memory during swing, and makes your muscle more stronger.
A few minutes a day helps naturally train your concentration and reflexes for more successful strikes!
When you finish the training and remove it, you will get faster swing speed and stability.
This tennis hitting aid can be used anywhere there's space wide enough to swing.

Specification:
Name: Tennis Topspin whistle
Color: Black
Size: 11.2*14.4cm

Package include: 1 X whistle

Note:
There is 2-3% difference according to manual measurement.
Please note that slight color difference should be acceptable due to the light and screen.