When combining accessories and adapters, the low load capacity / payload is relevant.
Bikepack X Compact Waterproof
Contour Saddle Adapter · black
compact bikepacking bag – simply to click on saddle
Compact waterproof bikepacking saddlebag that can be mounted and removed in a flash without needing to fasten countless straps. Simply click the bag onto the Contour Saddle Adapter and fix the Velcro loop around the seatpost, the bag sits securely without swinging. Through this attachment paired with the stable internal structure Bikepack X bags have a higher load capacity of up to 4kg. The volume can be varied by the practical roll closure between 4,5 and 6,5 L, so that the contents in the padded main compartment are protected from slipping. The combination of lamp holder and reflector provides better visibility.
These bags were developed for bikes without carrier. They provide lots of space as well as good protection against dirt and water.