The family of mallet percussion instruments includes the glockenspiel, xylophone, marimba, vibraphone and steel drums. These instruments have melodic and harmonic properties unshared by other percussion instruments. With the exception of steel drums, these instruments have bars that are thin in the center and wider at the ends, being hollowed out from the inside. The bars are suspended by a cord or rest on a padded support at nodal points — these are points where there are minimum interference with the resonance of note.