The top box is a SHAD SH40 and it pretty much is a perfect fit for both the bike and the slightly modified Ventura Sport Rack and bike specific L-Brackets. The modification of the Pack Rack is the removal of the tubular backing that normally holds the Ventura bag. If you were going to purchase the rack from scratch, you only need the Sport Rack, which is identical to the Pack Rack but without the high tubular backing. This is what the bike came with (I purchased it second hand). That is the Ventura Pack Rack: Side-on shot with the top box: Front-on shot with the top box (the SHAD was a perfect width - not too wide or bulbous like the Givi): SHAD SH40 up close: The top box platform: I chose the SHAD SH40 because of it's size and narrow shape, which fitted the bike very well and could take quite a bit of shopping, and my backpack on my daily commute. The locking mechanism is simple and strong. The SHAD itself is great quality is still like new. The platform secures very well to the Ventura rack, and the bolts clear the rear seat easily. However, the rack system is designed only to be used with a soft bag that has a bit of movement on the rack during acceleration and deceleration. A top box will put more direct force on the rack than a soft bag. This is because the top box is a fixed, rigid weight. After almost 16 months of constant use, one of the pipes broke from fatigue, just below the platform join: It looks like this point suffers the least flex, resulting on a lot more stress on a smaller area. I was lucky that this breakage occurred during some slow Sunday riding to the local markets, and while the top box only had a near-empty backpack inside. It didn't fall off the bike and I was able to poke a small bit of branch into the opening to hold the two pieces of tubing in place. So, a word of caution. It is likely not a matter of if, but when, the rack will crack. This break may have started out as a small crack, in which case, if I had been looking for it, I could have caught it before it broke completely through. So, I'm about to order a new Sport Rack (this fits into the L-Brackets that are fixed to the bike), for $90. I'll look at securing this 90deg angle with a cross strut that can be clamped to the piping without penetrating the coating.