Our burra burra stabilizer seatpack 20 is the largest in our line which means that you can say goodbye to the cumbersome weight and handling of integrated rear racks instead it affixes to your seatpost via an engineered aluminum stabilizer arm that minimizes any bouncing or side to side swaying under load the pack itself features a welded roll closure design thats highly resistant to inclement weather while its larger size 55x19x10cm makes it ideal for mid to larger sized frames