Some repairs as soundpost patch, opened seam and crack repair must be done on the back plate over the ribs. Clamping the cleats and patches is then, due to the rib height quite a tricky task. Using these over the rib steel clamps is an option for accurate and deliberate executing of these tasks. The lower pad with silicone cover can be used in direct contact with the varnished surface of the repaired plate without risk of harming the delicate surface. A short opening ensures a precise focused clamping action, although the clamp is drawn over the ribs. Different depths ensure the clamp can reach always exactly any wanted spot on the back of the cello resp. bass.