That is a PRM rack.I am going to add a rack like this for a small tank of gas for my gas-aholic YZ and for a small padded (and completely removable) backrest to help keep my 6-year old son on the bike with my GF when we go for family rides. I like this one better than the PRM one:
I bought one for my Outlaw, it broke like 4th ride, had it welded and beefed up. couple more rides it broke again. More welding and I added some support rods to the frame and all was good. When I bought my XX I had my welder buddy mod it to fit the Honda. Hasn't broke yet.
The one that they sell for the Honda is the same rack just a little different mounting.
So all I am saying is if your going to count on that rack to keep your son on I would watch it very closely.