I purchased the 20L Rucker 4.0 directly from GORUCK 14 months ago. I've used it for a variety of workouts including a few 30-lb half marathons, some 40-lb 5-milers, and a bunch of 50+ lb shorter walks/hikes. The pack itself it extremely well built and has handled weights up to 65 lbs without issue. I've mostly been using Yes4All Adjustable Ruck Weights (from ngclab.com) because they're the same size as the GORUCK plates but half the cost; just make sure you verify the size of the Yes4All plates if you go this route as they have several sizes. I can get 40-lbs worth of the Yes4All plates (4x 10-lb plates) in the designated plate pockets. To go heavier, I will add another 10-lb or 25-lb iron plate from my regular barbell set - that'll go in the regular part of the pack. I imagine that you could put a couple more Yes4All plates in the designated plate pockets, but I only own 40-lbs of them at this point. I bought the GORUCK pack because I was looking for something that I could run with that would have minimal bounce, but still hold at least 30 lbs and maybe a jacket and some food. This fits the bill for all of that. I ran my last half marathon with 30 lbs in 2:34 (11:45/min pace). I could cinch the pack close to my back to minimize bounce and I could throw my jacket, cell phone, water, and some food it without any problem. I wore a t-shirt with it to prevent chaffing; I wouldn't attempt running that far without a shirt between me and the pack. I added a cell-phone pocket to one side and a water-bottle holder on the back. I tried putting the water-bottle holder on the side, but it chaffed my arm after a short distance. Both of these add-ons are not extremely accessible while wearing the pack, but I don't like using my cell phone while training, and I use the water bottle holder to hold a refill for my hand-held water bottle. My only issue with the pack is the shape of the straps - they're too flat for long-distance heavier rucking. As the weight of the pack increases, it puts more pressure on the side of the straps that is closest to my neck. Tightening the sternum strap can help, but I can only tighten it so far before it restricts my breathing. I'm not a huge guy (5'9", 160 lbs), but the straps seem to fit someone with more square shoulders than I have. Note that I did not remove a star from my rating for this because this is still the best pack on the market for what I'm looking for. The straps only start to become uncomfortable when I'm carrying more than 40 lbs, and honestly it may be difficult for any pack (without waist traps) to be comfortable at more than 40 lbs. One final note... I purchased the waist strap hoping to take some pressure off my shoulders and further reduce bounce. For me it was a waste of money. It didn't reduce the bounce at all when I ran. The waist strap did, however, continuously pull up the back of my shirt so the pack could chafe my lower back. Maybe it would be good for heavier walks/hikes? I would definitely recommend this to anyone looking for a small, minimal-bounce rucking pack. I have a weighted vest as well which is great for CrossFit training and the Murph, but this GORUCK is way better for rucking, especially running. Mine has many miles on it and shows no signs of wear.