Jardine 18-QMI1 RT1 Quiet Module Insert for 2-1/4" Tip The QMI is a sound attenuation device that installs easily in under a minute You can now have the best of both worlds - maximum power from a race core or the neighborhood friendly tones of the QMI unit Specifically designed for race core equipped models The QMI allows you the option of substantially decreasing the sound level of your racing system when you need to Constructed from aluminum billet and CNCd to exacting tolerances, the module features a red high temperature silicone O-ring to assure proper sealing