These are simply the best bags we have found and tested.  Super durable.  Should be the last bag you have to buy.
 
The capacity of the bag can be adjusted, the nomal capacity is about 50L, the unfolded capacity is about 70L, which meets the needs of medium and long-distance cycling
Stable border design, sturdy four point fixation. Thick Steel wires are used to support both sides of the bag to ensure that the bag does not deform or shake
Powerful MOLLE expansion system, the front, side, and top of the bag are designed with molle system, which can accommodate a variety of external items. There are multiple compartments inside, including a dry wet separation compartment and a 14 inch laptop compartment for easy storage of items
Comes with rain cover, fix it on the bag with the buckles on two sides of the rain cover
Accessories: Bag*1, rain cover*1, 47.2 inch shoulder strap*1, 22 inch strap*4, 37.8 inch cam buckle strap*2