This is a stainless steel replacement ROTOR which screws onto the 2 piece, 6 bolt, 280mm rotors found on later bevel drive 900SS and some Darmah.
You can flip around and mount it whichever direction is needed. So there is no need to specify LEFT SIDE or RIGHT SIDE when ordering. Please just choose if you want 1, 2 or 3 rotors. You will also get a fastener kit with 9 bolts and 9 of the proper wavy lock washers for each rotor ordered. These 9 fasteners are used to attach this rotor to the stock center carrier which you can clearly see where the red arrows point in the photo of the Darmah on this page.
NOTE: The detail photo showing the front end of a black and gold Darmah shows the carrier that this replacement disk bolts to along with the original disk for clarity. The disk part shown on the bike & on the main photo here is what you are buying - the rotor that the brake pads squeeze, not the carrier.