Ortlieb  Frame Pack - 4 Liters

Great bag, I put it on my e-bike for stashing things while commuting. Fully watertight, will keep whatever is in it dry in any weather. Construction quality is high. Lots of adjustability to attachment points ensures a good fit. Unfortunately it got stolen off my bike but I’ll probably buy another. Has enough space for a mini u-lock, a hat, a water bottle and other odds/ends

Excellent build quality. WaterPROOF. Snug and robust attachment to the frame that makes it look like it belongs there. The zipper was really tough to open at first (I thought I was going to break it) but it's wearing in quickly and hasn't been an issue. I've had another similar frame bag that worked very well for a third the price (Moosetreks) but this is a bit more waterproof and the material seems more durable. I have an ebike battery in this bag, a standard triangle battery that was removed from the plastic case. It just fits through the zipper but there's easily enough room in the bag for some padding and the wiring. It takes some patience and finagling but it's a very suitable bag and I don't worry about water. I cut a tiny slit in the bottom for the cable. Costly but I believe I'll get my money's worth in longevity.

I bought this for my e-bike to keep a handful of things in when riding around town. Construction is very high quality and the range of straps and places to put them makes it easy to fit on. Unfortunately when my bike was stolen I lost the bag but going to buy another. Waterproofing is great even in heavy rain.