This is a complete, original, throttle slide for the Mikuni BDST 38 carburetors as used on, amongst others, the Ducati 750 Monster.
Mikuni part number: N213109
Ducati part number: 13440011A
Please note that this is the complete slide.
We can also supply the diaphragm-only which can be found HERE.
Although these carburetors were originally delivered on the above mentioned models of motorcycles, they are often transplanted onto other bikes and engines so the range that these diaphragms might fit is much broader.
Alternatively, your bike might have been equipped with different carburettors during its life so please verify that this slide will fit your bike.