I have a smaller version of this tail bag, the roll bag. I bought it as a
set along with a taller, more rectangular bag to use on my Shadow. This bag was designed to attach to the top of the larger bag using 4 short straps. It worked great on the Shadow because I had a luggage rack to attach it to. The quality seems pretty decent, and the set came with a waterproof cover.
However, I do NOT have a rack on the CTX and I'm not sure the Honda one is that useful, because it seems so small. I went to Cycle Gear and got the
Sedici Veneto tail bag. I haven't been able to actually use it so far, but I bought it and packed it for a camping trip that I had to cancel (sorry, Bob). The Veneto is amazing because it has so many attachment options--it even includes a pair of bungee cords tucked into a compartment in the bottom of the bag. It has straps that I was able to put under the CTX seat to do most of the holding. The Veneto also has sections that unzip to expand, especially vertically, which made a HUGE difference in its capacity. The Veneto also includes a waterproof cover.
I use the cylindrical MotoCentric roll bag to hold my rain gear, a full set of extra dry clothes compressed in a big Ziploc bag, and a set of 4
REI straps. It's packed full, but is perfect for that stuff and I can stick it on top of the Veneto bag and pull a bungee net over the whole thing. The Veneto even has straps that run up over the Motocentric bag to help hold it on, too. I hope to try it in a few weeks when I will be making another trip to the same area as my previously-planned trip.