Very difficult to use.
perfect, just as in the picture. It's a good size for a B17 type saddle, perhaps would stikc out a bit on the sides on a narrow racing saddle. Good capacity for a warm layer or for tubes, patches, tools, food... for a day ride. Be aware though, it is NOT expandable, at least not very much, so if you are looking for one of those saddle bags that blows out to ridiculous sizes to fit your whole camping kit in, look elsewhere (or at least at a different size. I have not verified the liters capacity nor the waterproofness, but seems water proof and it is plenty big for me and good quality, stays on tight, has a slot for a clip on rear light (not super strong looking but after a week of riding I have not had my light come even close to falling off). Good product, I recommend it.