Osprey Ultralight Raincover for BackpackBluesignBluesignBluesign

I bought the Medium and it is a great fit for most 45-55L packs. At the upper end 50+ liters it is maxed out and will probably not work if you have things strapped to the outside of the pack but should accommodate bottles in side pockets. Osprey is zero help in giving actual dimensions but if it helps anyone, the Medium is sized as follows, measuring between the stitched seams: 29"h x 12.5"w x 11.5"d. Made from a light siliconized nylon fabric with taped seams that packs up super small and will remain waterproof for a long time. This material can be poked and abraded fairly easily so try to be careful with it in brush or when setting it down but it is reasonably durable. If you need higher durability, bite the bullet and get a heavier pack cover.A very nice feature of this pack cover that is not advertised or pictured often is that the bungee cinch cord can be looped over the hip belt (an opening on the cinch channel on each side). This keeps it from coming off in wind or when you need to get into the pack while not wearing it...simple idea to make it simpler to use. There is also a small light 3/8" clip buckle near the top, attached to the cinch cord that can provide additional security from it being blown or pushed off of the pack. Great product and I like it better than the similar Sea To Summit pack covers, and it's costs less, too.

I bought the Medium and it is a great fit for most 45-55L packs. At the upper end 50+ liters it is maxed out and will probably not work if you have things strapped to the outside of the pack but should accommodate bottles in side pockets. Osprey is zero help in giving actual dimensions but if it helps anyone, the Medium is sized as follows, measuring between the stitched seams: 29"h x 12.5"w x 11.5"d. Made from a light siliconized nylon fabric with taped seams that packs up super small and will remain waterproof for a long time. This material can be poked and abraded fairly easily so try to be careful with it in brush or when setting it down but it is reasonably durable. If you need higher durability, bite the bullet and get a heavier pack cover.A very nice feature of this pack cover that is not advertised or pictured often is that the bungee cinch cord can be looped over the hip belt (an opening on the cinch channel on each side). This keeps it from coming off in wind or when you need to get into the pack while not wearing it...simple idea to make it simpler to use. There is also a small light 3/8" clip buckle near the top, attached to the cinch cord that can provide additional security from it being blown or pushed off of the pack. Great product and I like it better than the similar Sea To Summit pack covers, and it's costs less, too.

I have an Osprey backpacking backpack and this rain cover was a perfect fit for it and very easy to put on and take off of the backpack. It’s lightweight and folds down nicely into the attached storage pouch. I’m very pleased with this product and would recommend it to others.

I bought this product for my Osprey Ariel 55. My pack is size small so it is technically only 52 liters. I initially bought the large rain cover because the description said a large started at 50 liters. When I got it, it as huge - obviously to accommodate larger packs. I liked that I would have a lot of room if I wanted to strap a lot of stuff to the outside. However, since I don't typically do that, I exchanged it for a medium. There is a huge size difference. The medium was definitely more snug and I liked the fit. I didn't want my cover getting caught and snagged on trees when I go backpacking so even though I probably cant strap much on my pack, it's great. I still had some room to attach on smaller items to the bottom and I would still be able to put rain gear in the front stretch pocket and water canteens on the side. If my pack was any larger or even a different shape, I might have had to keep the large.Also nice because there are strings that go around the hip belts so everything stays in place. The material definitely seems durable and I haven't tested in intense rain but hold up to humidity and light rain very well.