Ortlieb Seat-Pack QR - 7.5L Dark SandOrtlieb Seat Pack QR 7. 5L Dark Sand. Thanks to the unique Seat Lock attachment system the Ortlieb Seat Pack QR is quickly and securely mounted and just as speedily removed completely residue free. An adapter even enables the use of a dropper post making the innovative Seat Pack QR suitable for a variety of bikes. The internal reinforcement and five compression straps ensure that the contents are packed tightly and securely. A valve with a handle