This bag was made for cyclists. I'm selling it because I no longer ride a road bike after buying a motorcycle. 1. The biggest feature is the Wind Pass function, which prevents back sweat and allows for a comfortable ride. The venting space is also adjustable. 2. You can choose between a regular size and a small size bag depending on the amount of luggage you need to carry. 3. A rain cover is also included, so you can ride with peace of mind on rainy days. 4. Parts for attaching a helmet come out of the lower pocket of the regular-sized bag. See the photo. You can attach your helmet to the bag while walking after getting off your bike. 5. There is a hole in the back of the bag to allow the straw of a hydration tank to be passed through. There is a crack in the waterproof processing of the zipper on the center outside of the regular bag. There was a website that explained it in detail: [https://blog.worldcycle.co.jp/20130607/3307/](https://blog.worldcycle.co.jp/20130607/3307/)