I don't know if Happy Trails makes them this large.
These were made by inmate jakewojo as a college design progect. He made these big ones and soime small ones and a rack to hold them all for a KLX 650. With the big boxs on the sides and the small ones stacked on top of the rack , well there was plenty of cargo space. The big boxs will hold my 7 and 5/8" full coverage helmet when I'm at the watering hole.