Bicycle Bike Cycling Sport Waterproof 10L Rear Seat Bag Black
It can also be used as a regular bag after parking the bike.
One can carry it by hand or shoulder due to its multiple functionalities
Nice room for things in main compartment
Handy drink pocket in back,Fits easily on the back rack, and easily removed also
Nice side pockets for repair items, sunglasses, etc
Velcro straps that hold onto the rack no matter what - Handy carrying handle on top