Brembo rear master cylinder, 15mm (~16mm) that was used on many models from late 1980s until after 2010. Some of the common models using this are: LeMans 1000 1984 to1987 (LeMans IV), LeMans 1000 1988 to 1993 (LeMans V), 1000 S, V50, V50 II, V50 III, V50 Monza, V65C, V65SP, V65TT, Lario, California 1100, Jackal, EV, Stone, Stone Tour, EV Touring, Special Sport, Bassa, Aluminum, Titanium, California III, SP III,California Special, California Vintage, Strada, Mille GT, substitute for 19667000 and 30666960. 50mm center to center mounting holes.
Note: The actual diameter is between 15 and 16mm so may be referred to as 15mm or 16mm and is interchangeable.
Note: Brembo technical data specifies DOT4 brake fluid