Form and function
I thought case liner bags were a waste of money ... till I bought a set. If it fits in the bag, it'll fit in the case. Makes packing and unpacking very convenient. These bags are semi-rigid and form to the cases very well. To the point of having to work the bags into the case even empty. On my wish list ... Some organization pockets. There are external side sleeves, but putting in a phone charger and cable makes it difficult to slide the case into the cases.
Inner side case bags
I recently purchased these bags from KTM twins and could not be happier. The fit and quality was what you would expect from the KTM brand and I received the order in a few short days. I would recommend them to anyone with the stock panniers.
KTM 1290 Side Case Luggage
I bought this luggage for my 1290 Super Adventure. They fit inside the side cases perfect and still leave a little room inside the case for my tools and stuff. They are very well made and expect they will last for years.