I have a silca and a silca seat roll.  It's better than any seatbag I have ever used and I can keep a multi tool, patch kit, a tube and some cash in it.

seat roll:

https://silca.cc/collections/packs-on-bike-1/products/seat-roll-premio?variant=25057215816

 

tool:

https://silca.cc/collections/mobile-repair-1/products/italian-army-knife-venti