Bottom line up front: Great bag. It is durable, functional, and flexible. For me, it is just perfect for all aspects of my riding. I have the magnetic one just in case someone is wondering. Yes, you will need a ferrous material tank (i.e. not composite and not aluminum… but steel… seems obvious right?)I like to find thorough reviews on my motorcycle gear so this is what I am aspiring to with this review. Sorry for being long winded.Background info:Bike: '09 Kawasaki EX-500 (Ninja 500R)Location: NE AlabamaRiding seasons: Year Round (when bike will start) - lots of rain in late fall, winter and springRiding type: Daily commute (all-weather, 20-30 minutes), joy riding (hours)Bag Review:Best investment I have made for making my bike truly utilitarian. I ride frequently and this thing is perfect. It is has great volume, the right kind of pocket/organization, and a great strip-map holder. It is highly survivable as well. Important features (in no particular order):• Map holder: I use this all the time and on my bike, the bag sits in just the right position for me to be able to glance down while riding. It is excellent when stopping. It is perfectly secure on the bag so no worries about it separating. I have put my phone in it before but the glare across the transparent plastic cover makes this kinda pointless in my experience during most conditions. It is a little frustrating at times to get a map in and out of the slot. It is a good idea to keep a dryer pack (i.e. one of the ones that come out of a pill bottle) in it after it is been damp or else sliding the map in and out is a real pain due to the moisture.• Expandable: When you open this thing up the full 18-L you can pack enough for a day/over-night trip. When it is full open, you are “reaching around” the thing and there is no chance you could get into any kind of tuck position, but if you are carrying this thing fully loaded, then you are not typically in the need of the full tuck.• Pocket organization: I think this bag is well balanced; not too many pockets but enough. It works great for grabbing a few things from the grocery on the way home from work (though I recommend getting Cortech’s tail bag and saddle bags as well for anything over a single bag’s worth of non-bulky stuff. I think I have had two 2-L bottles in there on the way to a social function. It has three penholders plus a small flashlight and blackberry-sized/shaped holder (which I use for my mini-power pack). The main pocket is big enough to hold an iPad and charger plus a tightly folded pair of socks, underwear, and a t-shirt in its unexpanded state and is open and flexible enough to support a few oddball shapes. I usually carry all my documents in there and I usually keep random things in my side pockets (e.g. my helmet’s chin skirt, a pair of sunglasses, a visor cleaning cloth and spray, and maybe my little plastic side stand foot that I carry to keep the bike from melting through the asphalt). The side pockets are not quite big enough for me to keep my aerosol can of chain oil, but that often ends up in the main bag or the saddles if really necessary. If I am not carrying my tail bags, I also stick my rain-suit in there in the summers. I have never used the spare visor pocket but it will work for it. In the winter, I can carry a pair of gloves, dry socks and a spare pair of thermals since they compress so much. That key ring clip is way more useful that one things about on a regular basis. I never use it for a water bladder storage because I just carry a small one on my back since I have not figured out any better way to actively drink while on the back than to pass the tube over my shoulder (or under my armpit) and under my chin strap into my mouth. That is just a hard problem to solve to my knowledge.• Magnetic attachment: All right, this and durability is where the metal meets the road for me on this bag. Let me admit that I am at fault for all failures of this system. The two magnetic strips on the side are plenty strong enough to hold this bag to the bike. When I first got the bags, I was afraid it might be too strong because I thought it might help tip the bike over when I went to park the bike on precarious surfaces. However, it is not too strong. The ONLY problem with this bag is that I find myself prone to forgetting to fold out the magnetic flaps and so it is sitting on the tank but not really adhering to the surface… I have personally dropped this bag on the interstate at 60-80mph three times when I go to do something weird with my arm like shake my sleeve down or something. My sleeve has grabbed something with a little bit of Velcro or I move my arm from in front of me and down in a swiping motion and whoop… there goes my bag tumbling down the interstate (#faceplam)… Again, it has ALWAYS been my fault for not securing it properly! This bag is great.• Durability: So if you have read this far, you are probably wondering what happened to the bag after each of those three interstate trips. It survived every time. That material is legit. It has been hit by two vehicles, one sedan and a semi (yes, I had to watch that one). When it was hit by the semi, I actually had my ipad in it. The semi’s bumper struck the bag first and knocked it off the side of the road and along the median. It was the last time I used the bag because there was a slice down the side of the seam just under the zipper that had been sliced open (i.e. it wasn’t a tear because were no frayed edges… the a sharp edge of the bumper literally sliced into the bag apparently. The iPad SURVIVED. The bag was not run-over in the truest sense of the word but it was padded enough and durable enough to not break the iPad! If that is not protection, I do not know what is. The other two events just resulted in minor scuffs.• Construction: I just want to highlight that the zippers on this thing are very well made/engineered. They are operated easily, even while riding. They are smooth, rugged, and the secure.• Rain cover: The included rain skirt is wonderful. It has an elastic synch that does very well at all my speeds. I have never been riding while using the rain skirt and a map so I do not know how readable it would be trying to look through both clear pieces of plastic but it is food for thought if that is a concern of yours.• Off-bike Carry-ability: This bag is very convenient. The grab-handle at the back of the bag is big enough to grab with a gloved hand but not too loose either. It is not exactly a fashion statement to wear the thing as a backpack but the straps do work as advertised and it can be functional. I would not want to carry anything heavy for any length of time as the weight would be somewhat cantilevered out from your back and tends to ride on my lower back and press in there which just is not comfortable for me.I’ll be getting another one of these bags to replace the one that was hit by a semi. Ride on.