Soft sleeve with lid on the top is the solution you know well from trekking backpacks. You can also find it in the Classic series bicycle panniers. Convenient closing and opening Variable capacity...

The closure in the Expert series gives dual protection thanks to a combination of roll top closure and a lid. The lid is detachable and has adjustable height so you can load the pannier to your preference...

Roll top closure is used in  the Dry, the Twist and the Expert series. Protects from rain and dust Easy capacity adjustment by extra rolling Durable