I did a lot of research on this before i bought the frame bag. It is not completely waterproof if you are stuck in a complete downpour and have to leave the bag on the bike to hide indoors from the rain. It does how have enough room that you can throw whatever you are worried about into some plastic bags to protect them. It has enough space in it that I can carry a standard size Ulock and 6ft cable on one side of the bag and some bonk busters, pocket tool, tube and packable jacket in it. The straps are very good in that once you cinch them up the bags stays in place and does not move or sway. I will say go to manufacture website and create a cardboard template before ordering to check size and fit. Overall I am very impressed and will buy the larger bag for another bikepacking bicycle I have.
This pack is used for one or two day bike packing adventures. I mount it to a Specialized Diverge 58CM with Apidura's saddle pack and top tube pack. Very durable and well made. I have not used them in the rain so I can't speak to the water resistance. The grey color is a nice accent to my bike.
I have it on my Chargebike maxi 4.0 here in Idaho. I ride with it everyday and I'm a little abusive. It's very dry here and I ride everyday at least 40 plus miles. It certainly takes the heat and I have it full of tools and food. No moving around and stays put. Easy to take off and switch to my IRACYCLES 29'r in no time. This pack is awesome for anyone that is ready for the long haul. I'll be taking these bags plus more as I do the Tour Divide in 2019, so for now.....I'm really giving these bags a test for the ride, cause I don't need any bullsht once I'm out-n-about. Don't hesitate with Apidura.....great quality and craftsmanship.