In 1997, Peter Mach introduced the Mach One Shoulder Rest for violin and viola, surprisingly the first commercially available shoulder rest made out of the most natural of materials, wood. This model, the Mach One MO7, keeps the same famous ergonomic shape of the original Mach One wooden shoulder rest while minimizing the amount of material used. It is truly minimalist in design and concept. The main innovation is that it is made using a high-tech double-injection mold. The main body of the rest is resilient and strong, while the contact surface is made of a soft, grooved, rubberized compound similar to the sticky grip found on many toothbrushes. It is also easily washable! The sculptured shape of the all Mach One Shoulder Rests mold perfectly to your shoulder. The "S" shape fits comfortably on your shoulder and minimizes the size of the feet. These are molded from a single piece rubber and have a lifetime guarantee. They will never touch the ribs of your violin and will not scratch your valuable instrument.