Hi Steve,
It is off an ST1100. There are two bars, pointing North /South, under the Givi frame that bolt onto the grab handles mounting bolt holes at 85mm centers.
In the photo see at the top of the frame the front bolts have cover caps, the back ones you can see the allen bolt head. These bars are adjustable under the Givi frame
so if you can find mounting holes at 85mm apart [ N/S ] it should fit.
Cheers