Brembo PS13 Clutch Master Cylinder. For 22 mm handlebars.

M10 x 1.00 Thread 

Fits the following: 

CAGIVA Elefant 650 1985-1987
DUCATI 750 Super Sport 1990-1992
DUCATI 851 1991-1992

DUCATI 907 Paso 1990-1992
DUCATI Monster 600 1994-1999
DUCATI Monster 750 1999

DUCATI Monster 900 1993