A beater holder apparatus for a bass drum pedal enables adjustment of the amplitude of swing of a drum beater with respect to a drum head, comprises a beater holder that is configured to for radial adjustment with respect to the beater shaft. This invention also pertains to zirconium complexes useful in this procedure comprising zirconium and a ligand of Formula III or its enantiomerwherein J, R6 and n are as defined in the disclosure. The parameter may involve vibration, sound, pressure, fluid flow rate or other detectible characteristics of the toilet. A second portion of the line of separation may extend along a second portion of said opposing minor faces in a direction away from said one of said opposing major faces and towards other of said opposing major faces.