I just steered someone over to the nardi site this afternoon. Someone was looking for a horn button.
www.nardiusa.com ph# 1-888-868-0808 the guy is in south Florida. He also does custom Benz horn buttons. You may also try ebay.
A few words of caution on smaller diameter steering wheels. The Benz Doctor has advised that using these smaller wheels may cause the driver to damage the multifunctional turn signal lever. A $500.00 replacement. Another thing to keep in mind is the view of the instruments will be partially blocked.
My opinion on the Nardi, I think they look great! They also feel better do to the thicker wheel. The wood is a nice accent with the cars' interior wood.
1969 280sl 5 spd 1999 ML320 Gainesville,Fl.