This is the second one I've purchased. As I stated above, the top tube pack is light, well made, and stylish. It functions very well at the other end of the top tube fastened to the seat post. The only consideration to be aware of is if there is not much space between the headset and the stem you may have a hard time attaching the front strap as it is wide and positioned in the center.
Perfectly watertight for well more than my needs, and the Medium has plenty of space for tube, multi tool, tire levers, patch kit, a blood sugar test kit and glucose tablets for this diabetic. If you arent carrying the diabetes stuff, a packable jacket can be crammed in there.
The Apidura saddle pack is very well contructed with high quality materials, excellent fastening system and it looks good too. Easily carries several tops, shorts and essentials for a multi-day Inn to Inn trip. It even has room for a small narrow thermos! My pack is a size small. I like its versatility to roll down small
(though it looks a tad sloppy when folded small) it's surprising how volumous it is when expanded, plus the top bungies can hold down my pair of sandals or vest. When loaded, I notice the bike remains stable and not out of balance. The loaded bag moves minimally. I opted for the non waterproof version. If any contents need to be waterproof, simply wrap in a plastic bag. Apidura makes high quality gear that is practical.