The voice quality of Blueant Supertooth II is better than my factory installed Cadillac Bluetooth phone. Amazingly powerful speakerphone in such a small package. The listeners at the other end, who used to complain of muffled voice from my built in Cadillac Bluetooth phone, can now hear clearly and sometime have hard time believing that I am calling from handsfree phone. It sticks very securely to the magnetic attachment for the visor. Construction is a little bit like cheap Chinese products Because the metal cover for my on/off switch fell off on the first day. But overall it is a good product and you will be pleased at its performance.Update 4/29/2008: The speaker stopped working after a week. BlueAnt said the product is discontinued and they will replace with Supertooth Light