GU00823931070 Groove width about 2mm, groove depth about 5mm. Sold in 1 meter length. This "bulk" rubber edge trim is used on many models, for many different uses. Example uses include decorative covers, fairings, spoilers and starter solenoid covers. This is the one they would have used around the headlight hole on an 850 LeMans fairing, for example.
Guzzi part number 00823931070 listed for uses on California III, Nevada 750, Nevada Club, California 1100, Bassa, Calfornia Special, Special Sport, Aluminum, Titanium, Quota, Quota ES1100, Nevada Classic 750 IE, Bellagio, Vintage.