ACPRO1900 Professional Camera Backpack - Waterproof Padded Laptop Compartment with Rain Cover & Adjustable Straps - Durable Equipment Bag for DSLR Cameras, Laptops & Accessories - Perfect for Travel, Photography & Outdoor Adventures

So I ordered the 4000 and the 1900. The 4000 was large and had carrier (wheel) harness that you can take off. I think that bag is great for folks that want to take their gear on trips and want wheels or there is risk of it going in the airplane undercarriage. However, I like to carry my gear on my person on flights and I was afraid American Airlines would make me check it because they are sometimes rude. Long story short, returned the 4000.I took the 1900 on a week and half trip to the desert. I was able to pack the following:1. Two Pentax K-50 bodies2. Rokinon 10 mm3. My two Pentax Kit lenses4. My 150-500mm Sigma Zoom5. A macro lens6. A ton of accessories (a time lapse remote, SD cards, cables, a remote for selfies, spare batteries, flashlights...7. Tripod strapped to the side. I have a smallish travel tripod that extends to about 5 feet or so.The bag fit on a small regional plane over head with room to spare. I suspect the 2000 would fit no problem. 4000, not too sure (if it does, please comment).I messed up and couldn't fit my 17" laptop...I didn't read the 1900 description and that is my own fault. If you want a 17" laptop to fit, use the 2000 (weighs about pound more).Pro tip: The rain fly is in a zippered compartment on the bottom. Great points to attach to the bag so the wind doesn't take it out. See the pic. The Pentax K50 is water proof but I still use a cover for it (a dry bag from walmart) to prevent water drops from stick to the lens on rain that is rolling through.Hiking with this bag:1. My first hike was a 6 mile total hike in Anza Borrego with significant elevation gain and some sketchy steps. The bag invites you to overpack because it has so much room. I found the bag straps were a bit uncomfortable and dug into my arm pits (I am 5'4", someone taller or with a wider chest may not have this problem). You really need to use the sternum strap to prevent this. The 1900 has less shoulder padding then some other bags I have had. With that said, it wasn't too bad. I was able to carry two 1 liter bottles in the bottle holders, no problem. I was I able to take my rain coat, sweater, beanie hat and scarf (when the sun sets, it gets cold in Anza).2. I did the Joshua Tree Ryan Mountain hike with it. It felt really comfortable and stable when I was strapped with the bag. It was probably a mistake to do trail 1 without the sternum strap or waist strap. The bag seemed more comfortable in this hike with the straps on. See top of Ryan Mountain pic.3. Lake Elsinore brought a bunch of showers. The bag got really wet. So did I. Luckily, the bag had my rain gear and a built in rain fly (one of the nice features of the bag). See both pics of lake elsinore. The contents stayed dry and it was really nice to have the rain fly with attachment points to the bag so the wind doesn't mess up with it. I have bought after market rain flys and this was always an annoyance.Observations:1. I love the attachment points. I could put a water bladder outside or in the bag. I could strap lights, etc.2. TSA made me take my two bodies out for inspection. Thought it may not have been super fast, it wasn't too annoying to open up the bag at the last minute before going through the x ray.3. Some folks say that the bag makes it hard to rapidly pull out your camera. This is true. I keep the bag unzippered and just close the latched for easy access. However, I also hand carry my zoom when I'm looking for wildlife.4. Honestly, the bag is just asking to get overloaded. Be mindful of what you actually take on trail. Do you really need both bodies and 5 lenses? I found myself leaving things hidden in the car to drop weight.5. I wish the 1900 could accommodate a bigger laptop. In a perfect world, I'd probably own the 1900 and the 2000. Or just use a smaller laptop lol.6. Wish the 1900 had more comfortable straps.7. The 1900 doesn't come with the tripod foot support (or even a real tripod latch) on the side that the bigger Ape Mans have (2000 has it). If it does, please correct me but I haven't seen it. The tripod straps in to the side but it is a tight fit because it isn't meant for this use (and may break the bag). I don't like carrying the tripod on the bottom of the bag (straps that are there) because it ends up smacking me while hiking. Perhaps I can adjust that somehow so it is more comfortable.8. Not once did I feel the bag would break on me. It is a tank.This bag will be my go to back for a while. It works for me. If I could do it again, I would get the 2000.