I'm sure I'm being a bit thick, but last night I spent an hour clicking on stuff on the Givi site without managing to get an iota of education about how their products work. Imminently I need a topbox, preferably that can stow two helmets, or one helmet and a pair of armoured trousers. That seems simple enough, I can find a rack doobery and a 45l topbox which alleges to attach to the doobery. The confusion comes later into the modularity of these systems with respect to panniers. Can you add them later? If you buy the wrong top box stuff do you scupper the pannier options for later? Is there anything which might help me understand?! Then I need to wade into the mire of heated products, boo.