Sometimes a shoulder rest will be too high for younger players (3 to 7 year olds) and they will have to use a sponge instead.  Created for students who desire a comfortable fit without raising the chinrest too high into the neck. Soft foam is contoured over the shoulder with extra padding at the collarbone.

The 'Original Petite' model.  The 'Perfect Shoulder Rest' (PSR) is an ultra lightweight foam shoulder pad designed to accommodate for the unique shapes of our bodies and instruments. These shoulder rests are designed to fit smaller 1/10 - 1/4 size violins. 

The PSR rests now come with the 'Magic Strip'. This adhesive strip allows the foam pad to safely stick to your instrument.  It can then be removed again and reused over and over again.  See the video here for full instructions:
PSR Video