The 2 layer construction of the AcoustaGrip Concert Performer is a key feature. The 1st layer consists of custom designed and produced acoustical materials, delivering superior sound and extreme comfort. The2nd layer is unique as it attaches simply with air to the back of your instrument using micro-air technology. Because it attaches with no glues or clamps, AcoustaGrip helps to preserve and protect the quality and condition of your violin or viola.fits 1/4 to Full size
3 multi-layers give this model maximum sound volume & increased resonation. Unique material allows secure hold without clamps so vibration of wood is not impeded; very comfortable, ergonomically designed and will not fall off. Removes easily to store in case.