It's a huge open sack mostly, with a top closure and a full side zip. It has a handful of interior pockets which is nice for small gear and most of them are accessible if you partially open the side zip (which is horizontal across the top side, then down the length so you aren't opening a vertical zip). There's a built in rainhfly/helmet tarp to cover the top, and a long skinny exterior pocket on one side. It has grab straps on all the sides that are heavy, reinforced, and thick.The backpack straps are very comfortable and fit like an actual hiking pack, with a wide padded waist strap with a small pocket on one side, well padded shoulder straps, and a sternum clip.The top is a pull-tight closure, but instead of having a button press to loosen the string it has a long toggle that's an angle pull lock. You just pull a tab on the end of the longer toggle and it tilts the toggle to allow the cord to slide thru easily and the bag can be opened. Great when your hands are burned.As most people have mentioned, it unfortunately doesn't have places to attach gear to the outside, though you might be able to partially rig something with the wings that's wrap around the sides.Interior size is enough to fit a rope in it's own bag, maybe two if you push it, and a very large gear rack with harness and shoes. Helmet is best attached to the top over the pull tight closure and strapped in with the rain fly/helmet tarp, but doesn't have to be.The exterior is waterproof (with the rain fly in place), so it's great for carrying a lead rope and a couple people's worth of indoor gear thru a rain or snow storm.Be aware that the backpack has an extra tough stuff bottom so it's safe to set on the ground, and positions it to sit at about your waist when you wear it as a backpack. For most people this puts the top of the bag even with the back of your head, which makes it very tough to wear a bicycle helmet and ride a bike with it too (for those indoor gym days, or if you're on a motorcycle). I wouldn't change this design, but it's something to know.