I have ridden about 50 miles over fairly rocky terrain and this bag has held up great. It doesn't look like there are any signs of serious wear. The bag attaches to your seat using neoprene and velcro straps - they are surprisingly sturdy. It has a little outer pocket for your multitool. I have a Crank Brothers tool that is as big as you can with that pocket. It seems like it is a quick access type thing, but with the main body packed, it is hard to get the multitool out. The inside fits a CO2 cracker, extra CO2 cartridge (in addition to the one in the cracker), thin 26" spare tube, and Pedro's large yellow tire levers. I jammed a patch kit inards and powerlink in there too. It is real tight, but zipped shut and is pretty much perfect as an emergency toolkit when I don't want to wear a pack.