The WonderThumb slides onto the thumb and transfers the support of the neck of the violin directly down to the base of the hand. This eliminates the possibility of the violin slipping down. The WonderThumb allows you to remove the worry and reduce the tension.
No need to squeeze your hand to prevent the violin from sliding down the thumb. The hand is now allowed to RELAX.
By keeping the neck of the instrument in correct position, the hand is then free to just finger the notes.
The thumb mounting allows for independent movement of the fingers, maximizing dexterity.
Whether you use a shoulder rest, or would like to try and play without one, the WonderThumb can add a significant feeling of left hand security with your instrument.